I'd say be wary of anyone who:

-is between 18 and about 24 or so. They're still quite young, may have radical opinions and may not be sure about their sexuality just yet.

-says they've recently come out. They might not know what they want.

-people looking for friendship first, then maybe a relationship. If you find someone sexually attractive from the get go, it can make something that's just a friendship and nothing more heartbreaking.

-(kinda obvious but people who) use lesbian and any other term along with it (such as bisexual lesbian, asexual lesbian, demisexual lesbian). They're likely to be unsure of their sexuality and/or woke.

-has everything littered in rainbows/pride merch, or looks overly excited over these things in pictures. It's a performance more than anything, and one to be wary of as the person may be a straight person trying to be cool.

-use terms like 'gay af', 'baby gay', 'slay/yaas queen'. Anyone I've met who uses these is usually straight (queer) or bisexual, never heard an actual lesbian using these terms.

-has friends that are solely LGBTQ, no friends who actually identify as straight and not one of its many flavours.

-has coloured hair. Anyone who I've met on dates who has non-natural hair colour who claims to be a lesbian would immediately ignore me if I wanted a more serious relationship, which could mean that they weren't gay to begin with, just liked female attention and the attention being special brings.