I usually have yogurt once every few days, sometimes even every day. If you are trying to lose weight, get the low fat one's, as they generally have fewer calories (and of course fat!). Be sure to check the amount of sugar in it though, as many companies will just swap out the fat for sugar, which is doing you no good.
Good luck!
Oh, and check out my blog in my sig. I update it daily with weight loss and nutrition tips. Thanks!