Well, that's hard to say as your question is a little vague. We don't know what style you intend to sing, but it must be in key, in tune, with nice tone, phrasing and expression.  Beyond that, technically speaking, you need to use a good microphone, record in an acoustically adequate room, and adding a little plate reverb is always helpful.  In addition, a technique called "doubling" is very useful in making your vocals sound rich and full.  Here is a very good tutorial on that topic...

http://www.magix.info/us/get-that-professional-sound.online-training.31964.html

After you've done all of that, proper mixing and mastering of your completed track is very important as well.  Good luck!