15% is the standard. Good service earns more than 15%, poor service 10% or below if it's extremely poor.
I also feel that it depends greatly upon the price of food. If I feel I've received good service, I'll tip at least 3 or 4 bucks even if the food was only $10. In a college town, restaurants are very cheap because college students can't afford to splurge. Likewise, college waiters could really use the money, so give em a few bucks.
I feel that you can't really understand tipping unless you've worked at a job that takes tips. I worked as a valet at a really nice steakhouse, busted my ass all night in the cold, and cleared $150 cash a night during the winter. One extra dollar per customer can make a big difference for people.







