how do I flirt with girls? they think i'm just nice.

There is an art to flirting. It's mostly about the underlying message that you give to the other person. Complimenting will say "I'm interested in you, I've been giving you attention and like what I've seen". Having the right body language will say "I'm confident, interested, and open to you". Keep in mind what underlying message your body language, words, etc. are giving. It will take some practice so don't get disheartened, you'll figure out flirting as you go as everyone does.

All the best.
SEK

 

I think an initial-little-too-long-/-intense-mutual eye contact is a great way to start. when this happens to me i can't help but have a stupid big grin on my face for the rest of the evening.

my biggest barrier is similar to yours, i never get called beautiful or pretty ect. but i alwwwaaayss get called cute. cute to me means; animated (which i admittedly am), with child like charm and no sex appeal...!!

so after eye contact i am also stumped! share the knowledge if you work it out

 

Is this trying to flirt with girls you know are bi/gay, or girls in general, when you don't know?

Girls in general is tricky because the majority are probably straight and it probably wouldn't occur to them that you're flirting, they will just think you are being nice.

Otherwise - eye contact. A quick, bright, appreciate look/slightly cheeky. That's the best way I can explain it anyway. People in the UK often flirt by teasing, but I know that doesn't translate to most countries.

 

Lots of eye contact and smiles, if you're sat with them sitting closer to them, lots of complements, checking them out, slight touches like touching their arm leg or hand, wanting to spend time with them, talking or messaging loads, being interested in what they do, wanting to hang out all the time because you want to draw then in if you know what I mean

And as already said in the UK slight teasing