Refill their drinks when they start to get low.

Be very friendly. If you can joke around with them and make them feel comfortable, you will prob get a better tip.

Once you do it for a while you will have an idea before hand if the people you are waiting on will leave a decent tip.

For example, if they are running you all over the place, put other tables above them because chances are, they won't leave you shit.

Waiting tables is the worst job I have ever had. Good luck, if you get good at it, and work at a good resturant, you can easily make over 100 bucks a night.