Find your own style. Experiment with different ways of singing and different types of music. Find the one that fits your personality and makes the most of your voice at the same time. You want people to be able to recognize your voice when they hear it. If they can't, you might as well be someone else.
Embrace what makes your voice unique. You may initially think that a quirk in your sound is bad and try to get rid of it -- don't. Use it to your advantage. Adele is smokey and slides a lot and it works. Amy Winehouse was a little rougher around the edges and it works. Justin Timberlake is nasal and somehow it works. Whatever hand you got dealt, run with it.