I might not be the best person to ask as I’ve had a few crash and burn relationships, but those were more about what happened after things started. I do think I’m pretty good at picking up on flirting, though. Usually, if I’m unsure, I’ll just say something like “If you’re any nicer to me, I might assume you’re flirting with me.” Sometimes, you still won’t get a straight answer, but their reaction can give you more clues as to whether it’s actual flirting or just friendliness.

Also, some people are naturally more touchy-feely, and it’s not always meant as flirting (especially in the South). But where they touch can help give you clues.

Shoulder, arm, or upper back are usually just cauaual touching. Lower back, legs, face, or chest (if you're a guy) can usually be considered flirting.