Pretty much what the title says.

What are some good ways to flirt a little and just kinda of test the waters with a girl im just getting to know in order to gauge her interest in me, and what reactions should I be looking for in her in order to figure this out.

This is mostly for a situation in which you and a girl are kinda friends and you think there could be potential spark between the two, or they flirt a little and you think they might he interested, which is what its like for me with two girls i know right now.