Coupons, of course. Don't be shy. Restaurant coupons you find in the newspaper, phonebook, Valpak mailers or buy from outfits like Entertainment.com can really knock your restaurant check down to size. If you're embarrassed about using a coupon, check out websites such as Restaurant.com, where you can buy "gift certificates" for selected restaurants at a fraction of their face value.
Try it for lunch, not dinner. If you have your heart set on trying a new five-star restaurant in town, go for lunch rather than dinner. Many restaurants have similar menus at lunch and dinner, but lunch menu prices tend to be significantly lower, sometimes in exchange for slightly smaller portions.
Don't order the salad bar unless that's all you order. I love salad bars, but I've found that they either inspire me to overeat to the point of not enjoying my entrée, or else I don't eat enough from the salad bar to make ordering it cost-effective. My policy now is that I either order only the salad bar, or only an entrée, but rarely both.
You say it's your birthday? No, don't be a jerk like a guy I know who claims it's his birthday every time he eats out. Based on the number of free pieces of birthday cake he's received over the years, he should be more than 1,200 years old by now. But when it really is your birthday, check out a website for a list of dining establishments that give you free or discounted meals or other perks on your special day.
Eat where the students eat. College students major in cheap eats. You can usually find a selection of bargain-priced dining establishments surrounding a college campus, including inexpensive ethnic restaurants and street food you might not otherwise discover.