There are many ways to get around bad tippers especially in a small restaurant where you are likely to serve the same people over and over again. With a limited customer base you can often come to predict exactly what your tips will be, while learning how to get around the bad tippers.
Talk to your regulars, especially the people who come in alone. They will leave higher tips because they feel that they must. Many of these people can be transformed into big tippers given enough time and effort. A full fifty percent of your income may come from these regulars, so nurture them, cater to them, and do what they like, and your income will grow because of it.
Give poor service to those you know to be lousy tippers. Spend your time on the good tippers. Ignore the bad ones. I worked in restaurants for years and I have seen all kinds of bad tippers. One man who ate nearly daily in our place would only tip black women. Thats it, no one else. If you were a black woman and waited on him you got 2 dollars, otherwise you got nothing, not a dime. Whenever I got stuck with him I would bring him exactly what he wanted the first time and never check on him again.
People are more likely to tip if you watch them leave. This is because they feel self conscious. If you have to follow them all the way from the table to the checkout stand, talking the whole time. Only the most hardened bad tippers will be able to stand up to this sort of tactic.
If you are female then try flirting subtly with the old men, they will tip you higher, a lot of older men never get any attention from women at all. If you are male you should flirt with the older women for the same bigger tip.
If your restaurant is privately owned then consider talking to the owner about adding gratuity onto the check for your frequent non tippers. Plus gratuity should almost always be added for any groups larger than 5, and for any groups with more than 2 children. For some reason people think that children don't count when it comes to tipping, even though the children usually leave huge messes, and still get a plate and a drink just like the adults do.
Finally, you can always start working at another restaurant if you simply cannot make enough money at the place you are at. Serving jobs are really easy to find, due to the very high rate of turnover that most places have.