If a guy likes you, he is obviously going to make eye contact with you and talk to you. Those are the first give-away signs. However, guys are primal creatures and we have a tendency to eye-hump any date-able prospects. (If this is a problem, there are 2,999,999,999 others to choose from, but good luck finding any differing characteristics.) If you're unsure whether or not it's something more than just physical attraction, watch how he talks to you and compare it with how he talks/acts around other girls. If he's noticeably more nervous around you, or tries really hard to make stupid conversations, it's his way of showing you that he's interested. Otherwise he'd look away and start talking to someone else whenever he sensed it was too awkward and possibly not worth his time with you. In response, to let him know that you might be interested, say something back, laugh, whatever, just something to keep him engaged. (Not everyone's got game, so be patient). If you're still interested after this conversation and unsure whether or not he might be, then you should say something like "well this was fun" or "it was fun hanging around you, hopefully we can do it again soon" or something to that effect. DON'T be the one to suggest an exact activity/time, etc. That's his job. The trick is to let him know you're available, but not too available. This sounds counterintuitive, I know, but the girl being the one to make the first move and suggest plans is a huge turn-off to a lot of guys. The guys are the hunters. The girls are the hunted. It's science. If he responds "yeah we should, maybe a movie or something" something along those lines, try to wait for the "is it ok if i call you?" line. If he doesn't exactly give you the last line, wait until you're about to leave and then casually remind him that you enjoyed talking to him. If he responds warmly, then he should ask for your number. If he's not so quick on the draw, but still appears interested, then it's ok to give him your phone number. Some guys are really nervous and afraid to ask, so don't write him off just because he may not have asked you first. Give him 2-3 days or so. He'll be "too busy" to call you before that (more so because he, like every American male, saw "Swingers" starring Vince Vaughn, where explicit instruction is given to wait 3 days before calling a girl). In reality, he's staring at your number those few days, wishing he could call you. If he calls you sooner than 2 days: be skeptical. If he calls you the same night he gets your number: don't answer. Back to the Guy Market for you, m'dear. On the flipside of all this, he may try to give you his number first. This is ok, he's just doing it to show you either 1) that he's got a "busy schedule and he doesn't have time to initiate a conversation with you", or 2) that he's not a creeper, but a gentleman, and he wants you to call him so you'd feel more comfortable. Both are bullshit. But both are cool because now the ball's in your court. Wait 3 days before calling. Any sooner and you come across as needy and too available. Any longer, then...well... you're just kinda being a bitch. If he calls you first and the conversation's not embarrassingly awkward or anything, then you can suggest the plans if he's coming up empty. If you're the one that calls him first, make small talk and get him to suggest the plans.

Hopefully this gives you a better idea of how to approach situations with guys. Men are simple, predictable creatures. You have way more going for you. Make him work for it.