How To Increase Your Word Count

Describe the surroundings. When you start a new scene, set the stage! Put some description into what the place is like - how it looks, smells, sounds, etc. Describe what kind of condition it's in. Describe the colors and general atmosphere. Give a brief description of what the people there are like and what they're doing. Describe anything that would stand out and grab the attention of anyone who'd just come in having never seen the place before. (For more tips on this, take a look at Writing Better Prompts, Starters, & Beginnings: A Few Pointers.)

Describe your characters' body language and facial expressions. Pause the mental image you've got in your head and take a closer look at your characters. How are they sitting or standing? Are they relaxed or tense? Are they maybe trying to get closer, or trying to inch away? Are they still or fidgeting with their hands or feet? Describe what they're doing to your audience. Or if you don't have much of a mental image in your head to pause, ask yourself what their body language and expressions would most likely be based on what they're feeling and thinking right now, and describe that.

Describe anything else your characters are doing. Are your characters moving around the room at all? Are they drinking or eating something? Is one of them doing something like peeling apples or knitting a sweater? Are your characters standing or sitting? Where and how are they standing or sitting? Describe stuff like this.

Go wild with intimate scenes. Intimate scenes are the perfect place to cut loose with highly-detailed descriptions! If your story involves any of them, take full advantage of it! And remember, intimacy isn't just for your typical physical affection - even something like the bite of a vampire can potentially be intimate, too. Take a look at Basic Tips To Write Intimate Scenes for more tips.

Describe anything else that the POV character would be observing, and describe it. Is there anything going on that would grab the attention of your POV character? Perhaps there's something that would stand out for its strangeness or unfamiliarity to this character. Is your character examining something closely? What would your character feel, see, smell, etc.? If your character is examining an object, what does your character notice about it? What's it made of? What does it feel like? What color is it? What kind of shape is it in? Etc.

If you're in a roleplay, remember that every character is potentially a POV character. And with this in mind, describe anything that they might immediately observe if they happened to look at your own character.

Wherever appropriate, aim to show instead of tell. On Showing vs. Telling has more on this topic.

Explore the viewpoint of an overlooked character. You might give minor characters the time to express their own opinions if they haven't had the chance so far, or you might show them having a life outside of the main characters - even if only briefly. Even having them just casually mentioning things as asides can be helpful.

Take the opportunity to describe anything that might establish a little characterization. Dropping In Characterization Without Dragging The Story has more information on how to do this!

Make sure you're giving your important plot points the buildup they deserve. A lack of appropriate buildup is a common reason that many stories end up feeling too rushed, and making sure that you're giving something adequate buildup will definitely add to your word count. See On Buildup, Payoff, & Contrast and On Creating, Building, & Keeping Suspense for more information.

Write conversations that challenge your protagonists and force them think. Of course, you don't want to delay your plot progression with endless pointless banner, but conversations that actually make them have to think are probably going to be a bit richer and longer than ones that don't.

Of course, be careful that you're not adding too much detail just for the sake of adding detail. A good question to ask yourself is how the detail you're adding benefits your audience and helps them to better understand and visualize what's going on right now, or how it helps your characters and settings feel more real. Remember, anything that slows the story down or demands attention away from something important going on (EG, a detailed description of someone's physical appearance in the middle of a fight scene) is likely to bore or frustrate people. But as a general rule, adding in details like those described above where they are relevant and useful is always a good way to go.