1. As long as you dance with rhythm, don't worry about it too much... don't try to watch a Michael Jackson video and perform every move that he's done badly and off beat, that's the worse thing you could do...
What I do recommend for dancing is watching Usher videos... out of all the music I've studied and been a part of, he has some of the best and less blatant moves that you can incorporate into a club... also, try to avoid the whole Justin Timberlake videos, since everyone does the same little hand thing to every song... also pre-set routines aren't good, like guys who've learnt to do a little breakdancing, then run the same move to every song... just looks outta place
"Darrin's Dance Grooves" is one of the best instructional dance videos around... I know a bunch of professional dancers who all own copies to it...
2. When you walk into a club or any venue you make your presence known... just scout around the club see what's up... be seen, see what girls you're feelin', check 'em in the eye first, show that you're confident in this environment...
3. Chat up lines on dancefloors are a little hmmmmmmm... clubs and parties are generally very shallow environments, things are done on a looks basis, because with high volume music, it isn't the environment for conversation...
If the opportunity comes up to impress with your conversation, then take it and be sharp with what you say... my most recent example would be last week, when this 6'2" stunning blonde approached me when I'd just got into the club room of a venue with a friend...
She asked me, "Do you not think it's kinda gay, 2 guys dancing together?"
I could've backed off and cowered, been shook by the comment... but I held her eye and came back with, "You see, for most guys it might be a problem, but you see, me & this guy are so confident / comfortable with our heterosexuality that it ain't a thing"... and she loved me for it, needless to say things progressed late into the night...
There's most definitely a learning curve there... when you first start out in the club scene you're unlikely to be the best dancer, know all songs, know the definite signals, or have the wittiest lines... but over time as you experience and have basically a trial and error period, and build your confidence up, you turn out to be one of the most successful people in there, as long as you have the looks to match... if you don't have the greatest looks, don't worry about it, so you won't catch as many girls as the guys who do and already have the above downpacked, but just remember that different people have different opinions on what is attractive to them...