Attitude, attitude, attitude! If you're walking into clubs/pubs with no smile on your face, expect nothing. On the other hand, if you're walking in with a smile on your face, or even lauging, expect everything! (I personally like to wai (bow - with Sawadee Krup, "Hello") Which shows my respect for their culture.
As mentioned if you want the girls to be all over you like flies on the proverbial, then - dress nice, smile, be funny, and have a loaded back pocket.
There is a bar in Bangkok where at any given seforum.xxxe i'd have 10 no less than 4 girls having a great time together. Need less to say, half the mongers in the bar aren't too happy with me, because I take the girls away, so I don't fequent this bar as much.
Want to really impress them? Then learn some Thai, especially slang words.