Just be careful. You can ruin a good voice by stressing it. Extend your range, but pay attention, if something hurts don't do it unless you have a pro there helping. (even then tell the pro it hurts.) there might be a few things that will hurt when you do them that are good, but for the most part there are not. For that matter, there are things that won't hurt that will ruin your voice.

My recomendation is to sing in your range, and then meet a soprano someplace to take care of the upper ranges. This also gives you the ability to do some harmony, which is fun in itself.