The easiest way to do this, is be fun, sexy, have some personality, and make the user feel special! You're competing with all the other girls online, so you want to be unique. Just being hot isn't enough, you have to be able to interact well since that is what the user is paying for. You want to create intimacy between him and you, as he is competing against all the other users out there. Most times, the user will try and see why he should spend his money on you for tips or even more. Your job is to be enticing and teasing enough that he WANTS to spend all his money on you. That might be telling him a certain phrase, or maybe indulging in a fetish he has. Most of the time for tips, you want to show off a little bit, but not everything. So if he is an ass guy, maybe a quick flash, talk about things you like to do with your butt or different positions you like to be in, and pretty quickly the guy will be wanting more! If he is a boob guy, push your boobs together, squeeze them, talk about how you love to play with them. But don't show him your nipple yet! Make sure he pays you before, and once he does, keep him paying you as you play to his boob fetish.
Another user you'll find is a guy that just wants companionship. He'll take you private, and ask you questions about your personal life. Reveal to him what you want, but don't tell him anything that you aren't comfortable with. Ask him questions, get him to talk. Remember he is paying you by the minute, so the more he talks the longer he is spending time with you. Lot of these guys will use you more like a therapist then for sexual things. And if you're a good listener, you could soon have your new whale ;)