Digital is just another tool for artists. In order to excel in any medium you must first get a good grasp of the general fundamentals. Knowledge of light/color/composition all come from studying from life and from studying (and mimicking) master artists.
If you have specific questions, I might can be more helpful. But the best general advice I can give is practice practice practice. Learning art is just like learning another language. It's the visual language.
Here is a link to some resources you might find helpful: [link]
I use a variety of custom brushes to get a range of textures. I like to avoid the standard round brushes in Photoshop, simply because that tends to produce a "digital" look. Though with that said, the standard round brushes are perfectly capable of creating great art.
You can play around with all the brush settings, that's the best way to learn. Generally I try to paint with a big brush, that way it shows more texture. Here's a video on making custom brushes: [link]
And here is a nice page of general digital painting info and goodness: [link]
Gosh sorry for the late reply just been looking through your resources, trying out stuff on photoshop and doing loads of drawing.
Aaaanyway...I looked at the tutorial by daarken and found it really useful plus I went out and took pictures of things like mud, leaves and tree bark to use as textures for my brushes which is working great as well. Thanks for the info on brushes . The pages with videos on digital painting was good as well, I just keep watching them over and over as I work for reference.
Thanks for the help with this dude it is nice of you to be so caring . Thanks, the interview was great, now I only got to wait till September to come around .