Lots of renderings has to do with your style. I think the biggest problem I had when first started digital painting techniques, was I would try them, and not be happy with the results, so I would give up on that technique. Turn out this is not a good thing to do… 😀
One of the best digital painters I have ever watched work gave me a few things to try when painting in photoshop. The first thing he said, was when painting, don’t ever reach for the eraser tool. Just to start. He said you don’t learn from your mistakes when you get rid of them like that. He said you could paint over, or just ignore the spot, but never erase it.
When it comes to strict painting, different people will tell you different things. Some say the Smudge tool is their best friends, others will say not to touch it.
One of the best ways to learn, is to grab a tablet, and start playing. I try not to imitate others work, because if it doesn’t turn out the same (which it won’t) it is discouraging. When your looking for tutorials, look for one that focuses on the technique used, not the final project created.