Anyone using a pistol for self defense should use hollow point ammunition. Most ammunition that is hollow point (known as JHP, or jacketed hollow point) will be sufficient, although generally the more expensive it is, the better it is. For summertime, I usually recomment Speer Gold Dot, which is a popular choice for police forces. During winter, I recommend Hornaday Critical Defense. This ammo has a plastic insert in the hollow point, which allows it to penetrate clothing better, which is an important consideration in winter, when the bad guy is likely to be wearing thicker garments.
When you get your ammunition, be sure to test it in your gun, to make sure it cycles the gun properly. You don't want to perform your test on a bad guy, only to find out that your ammo choice jams your gun a lot.