Flirting.... TOTALLY EASY!!!
Smile, first and foremost, Smile Smile Smile, big grins, cocked to the side, sly ones, little ones, ones with a twinkle in your eye, a devilish grin... can all be flirtatious!
Laugh, laugh laugh laugh, everything from a chuckle to a hearty belly laugh, guys really like my evil laugh and it totally rocks many guys boats, but thats me, but don't be afraid to laugh at things, many things, your out enjoying your self, so enjoy your self.
Body language, sit back, relax, don't hunch over you drink unless your talking to someone and or you have caught the eye of a hottie, and wanna give the impression your talking about him to your friend as you flick your eyes back and forth from him to your friend..
try to keep your legs uncrossed, unless your good at being comfortable it can be a little off sometimes for guys who are uncomfortable and shy.
little comments, oh you can say anything, it just in how it's delivered, you can make a guy swoon in so few words when they are honest, upfront and delivered appropriately!
Also, gay men are very timid for the most part, all scared of rejection and hurt, so get some confidence for your self and walk up to them, DON"T DO LINES, gawd I hate when some guy who is unsure does lines, it doesn't work, just introduce your self, ask him if you can buy him a drink, smile, stand tall and proud (but don't be scared to come a little down to his level if he's shorter and things are going well), make a joke about your self, a guy will be immediately on guard and totally freaked that a guy just boldly walked up to him, getting him to laugh about you will set him at ease, shows you aren't "all that" to your self
when your confident and more seasoned you can deliver a line occasionally, do it with a cocky smile, an evil little happy look and in such as way as he knows your making fun and he'll totally get it.
You have a nice body (can't see your face though) so don't be shy, live, if you get knocked back you aren't going to die... SURE you might want to ground to swallow you up but it wont happen so put it aside and get on with it, it's just a no.