A common queer struggle is figuring out whether a girl you're interested in is also into women. While some clues can be obvious (like she wears a lot of flannel and short hair), other clues can be more subtle.
One big hint that she might be a lesbian is she talks about her sexual fantasies. If she always seems to be imagining herself and other girls together in bed, that's a pretty clear sign. However, it's important to remember that not all gay girls have the same sexual fantasies. In fact, some lesbians even prefer to only fantasize about men.
Another way to tell is by observing her body language. Some lesbians have more feminine body language than others. If she tends to twirl her hair a lot or wear dresses, she may be more feminine than average. Alternatively, she might have more masculine body language, like wearing a lot of shirts and pants.
Sometimes you can also tell by her behavior at events or bars. If she tends to hang out at a place that's known for being LGBTQ friendly or mentions a past partner who was a woman, it could be a sign that she is a lesbian. You can also try and see if she makes eye contact with you more often than other people or glances your way. Eye contact is a great way to show someone that you're interested in them. Lastly, you can ask her about her views on LGBTQ issues or about how she feels about women.