The Techniques & Tools of Magic
Information on how mages practice and cast their magic, what kinds of difficulties and limitations they face, and what one can reasonably expect them to use their magic for.
The Basics
Focused concentration is essential to working deliberate acts of magic, so mages are typically trained in various forms and styles of meditation to develop this. Mages are encouraged to practice this sort of thing on a regular basis; at least several minutes daily is considered a good idea.
Some mages just tell their students to relax and focus, and to avoid thinking of anything else while focusing one's entire attention on the task at hand. One mage from South Carolina had her students perform tasks such as hulling beans and focusing on the appearance and sensation of the beans and their hulls, and then after the fact imagining as many of the remembered details as possible and focusing as hard as one could on them.
Mages are also taught to absorb power from things, and to push it out of themselves again. In practice, this might entail being told to inhale and 'breathe in' the power of the sun and then breathe that power out into the air, or to let their feet absorb the power of the Earth like roots take up water and then push that power out through their hands and into another object, or something along these lines.
From here, the next step is to give that energy a purpose. A mage learning to heal may absorb as much energy as possible from a source relatively suitable for such purposes (such as a local river or the ground), and then push that energy out while concentrating on the person's wounds healing.
Objects may be enchanted in a similar manner. A mage might hold a pencil and spend a few moments pouring energy into it while concentrating on the pencil being able to help its user choose good words and avoid spelling errors.
Naturally, how well any these things will work depend on a number of factors. A pencil enchanted by a mage who isn't very strong or experienced yet might not make much of a noticeable difference. But if it's done by a more skillful mage, the user might find that writing an essay comes with only a fraction of the headache. Of course, most enchantments wear off of things after awhile, so that same pencil might not work as well afterward. (Lasting enchantments tend to require a lot more effort, and materials particularly good for holding onto enchantments don't hurt, either.)
This is the basic theory of how it works, but of course there are many variations out there. Some might incorporate music or dance, some might chant or sing, some might incorporate tools such as wands, or any number of other things that the mage finds useful or has been taught to do as part of a larger tradition.
Ranges & Distances
As a general rule, the more precise or fiddly the intended effect is, the closer the mage must be to the target. Thus for example, healing and repair magic requires close contact, with actual touch contact being optimal. On the other hand, freezing or heating a medium-sized object (such as a party-sized bowl of fruit salad), which is a less precise venture, can be done from several feet away by an experienced mage. On the other hand, freezing or heating a small object (such as a single strawberry) is best done from a few inches away. (Essentially, if you'd need small tools to get it done without magic, you're probably going to need to get close to get it done with magic.)
It's also best to be as close as possible to the target if the effect is extreme or invasive. For example, fully transforming another person into another creature requires touch contact. The same goes for trying to read or plant complex thoughts or ideas in someone's mind. (On the other hand, simple impressions or feelings can be affected from several feet away with several seconds of concentration.)
Resistance & Neutralization
Theoretically, any and all magic that directly affects someone's mind or body can be resisted and even neutralized. For example, if Bob decided to magically raise the inside of Alice's body to boiling temperature, Alice's simple desire to not die a painful and horrible death could put up a protective force. Depending on how much magical strength Alice could muster up, she might be able to reduce the temperature a few degrees to or even nullify Bob's magic altogether. Factors that go into how much resistance Alice can put up include how much she wants to stay alive, how strong her own magical field is, and how much she can focus on blocking or neutralizing Bob's magic. This is often referred to as magical counterforce, or simply just counterforce.
It's worth noting that people people tend to get very good at focusing when they believe they're in imminent danger, even people who aren't magically trained. Thus, a magically-untrained person can potentially fend off a well-executed spell cast by a mage with a magic field in the 4-6 range, or a shoddy one cast by a mage with a field in the 8-10 range. And even powerful, experienced mages making their best efforts can still be stymied if the spell is particularly difficult (such as with transformation and mind manipulation), or if the mage simply isn't very strong with the type of spell being cast (EG, someone with little to no affinity with ice trying to cast a freezing spell).
In addition, people can also wear charms and amulets designed to nullify or at least weaken malicious magic cast upon themselves. (Most amulets are not capable of completely nullifying a magical attack, but they can still lessen the effects enough to be worthwhile.) A very powerful mage with a strong affinity for the type of spell being cast might be able to get through all that, but it would likely take a little extra concentration and effort.
Because of the added difficulty in manipulating the mind or body of an unwilling target, many mages will try for more indirect approaches when using magic against others. For example, rather than trying to make someone spontaneously freeze, a mage may try to spill water onto the floor and freeze it to create a slippery surface for tripping up an enemy.
Tools and Items
Although physical items aren't strictly necessary for most magic, they can still be very useful. Wands and staves are a good example. Casting a fireball directly from your own hand must be done very carefully or else you risk burning yourself, but casting it from the end of a wand or staff can put a safe distance between your hand and the fireball. Wands are also good for applying magic to things you don't necessarily want to stick your fingertips near - for example, an injured pet scorpion you want to heal. They can also be used to apply magic much more efficiently; applying the palm of your hand to a cracked vase to repair it would result in quite a lot of wasted magical energy since you'd be channeling the energy into every spot your hand touched, but a wand can ensure that nearly all of the energy goes directly where it's needed.
Wands and staves are often made of wood, as it's usually fairly light and conducts magic well. Some woods are reportedly better for certain purposes than others - for example, elm supposedly has an aggressive temperament while apple is kinder and more loving. Wands may be decorated or not. Some wands are designed specifically for certain types of magic - for example, a wand designed for healing magic might be made out of wood and decorated with colors, stones, and symbols traditionally or commonly associated with healing.
Divination is done through many means, such as pendulums or pendants, decks of cards (tarot or otherwise), small stones or pieces of wood marked with runes or other characters. Mages might also create their own methods using whatever is available to them.
Items can also hold extra power for mages to draw on when their personal supply runs low. Crystals are a very popular choice for this, but if they aren't readily available, mages may fill bottles with any material that will suit their purpose. (Wands and staves can be decorated with crystals that serve no other function but to provide a power boost.)
Exactly what any magical item ought to be made from depends a lot on the purpose it's meant to be used for. Metals such as iron, steel, and aluminum readily sponge up aether but don't let go of it easily. Quartz holds and releases it fairly well. Glass absorbs it as easily as quartz, but is prone to losing it a little faster. Plastics are very resistant to absorbing it. Wood usually conducts it well, particularly along the grain. There are perfectly good uses for any and all of these, so it all comes down to the needs of the mage.
Potions
A potion is essentially a spell infused into something that can be consumed or topically applied. In theory they are fairly easy to make, but the practical difficulty tends to increase with the extent and strength of the intended effect.
When making a potion, mage will typically gather several ingredients that have some association with the intended purpose of the potion. In addition, the mage may take extra measures to ensure the effectiveness of the potion, such as choosing a relevant time or place for brewing it. (Which, while this does tend to help increase the potency and decrease the time needed to make the potion a little, isn't always practical and isn't strictly necessary.) While making the potion, the mage must concentrate on its intended purpose while pouring at least as much magical energy into it as it would take to cast the spell otherwise. (Mages may put in a little extra, since it helps ensure that the potion won't lose too much potency if it doesn't get used very soon, IE, within a week or so.) If metal pots are used, it should be made sure that they're already saturated with aether so that they don't end up soaking it out of the potion as it's brewing. (Some pans may be saturated simply from being in a highly magical environment for a long period of time.)
Anna Petersen, an experienced mage who studied reptiles, developed a potion to turn oneself into a snake for approximately three hours. Petersen's formula used powdered moth or butterfly cocoon (associated with transformation), powdered clay (associated with molding and shaping), a bit of fennel (supposedly used by old snakes to restore their youth), curled squash tendrils (their shapes reminiscent of snake bodies) and a pieces of shed snake skin (for obvious reasons). When possible, Anna brewed it when the moon was waxing, under the logic of "waning moons are for shedding skins, and this potion's for putting a skin on." She usually spent about an hour brewing a pint on the stove, which was good for three doses.
Of course, mages should always be careful that their ingredients aren't toxic and that their potions won't spoil before they're used. Magic or not, toxic and spoiled potions are still dangerous to consume!
Magic in Combat
Although many starting mages immediately imagine themselves as JRPG heroes, the reality isn't quite like that. Magic rarely works on the same grand scale that it does in video games, and the effects of magic don't always work out quite the same. Fireballs, for example, are primarily good for setting things on fire, which is often less useful than many think - tactical gear is usually designed to avoid catching fire, and if the fireball misses, it might start a fire that could be a threat to you, too. Striking one's enemies with lighting isn't really feasible because clouds are too large and far away to be manipulated into something so precise, and cursing someone with such extreme bad luck as to be instantly struck by lightning is likewise impossibly difficult. Magical blades, while technically possible, take quite a bit more skill to produce than shields and can still be nullified via magical counterforce once they begin to pierce someone's body.
Instead, magic is more often treated as a tool that can sometimes function as a weapon if necessary. Water can be magically frozen to create traps or shelters. A large rock can be shrunken, dropped into an fuel tank, and left to burst the tank once the spell wears off, or a small rock can be enlarged and rolled down from the top of a steep hill. Wind can be used to blind the enemy by blowing dust or sand in their direction. Illusions can make it appear that safe routes are dangerous and dangerous routes are safe, or can be used for camouflage purposes. Tricks like these are very useful if applied at strategic moments, which is why mages may wish to avoid spending all their magic on direct attacks.
Related SoulMettle content:
Magic: An Overview
Magical Tricks & Disciplines Of Note