Cant give you anymore advice than what colter and don gave just to practice more and more till you get it perfect(well not perfect as our renderings are never done) pretty soon after you've done a few you'll develop your own style and shortcuts to rendering.Btw once you start rendering your own wheels be prepared to spend alot of hrs.LOL
Great job so far though Colin email me if you need any tips or critique on your work in progress renderings.