There are many styles so head over to the tutorials sections and look up some of them and see if any match the style you are after. Also look at some maps and see if there is the WIP thread and find out which tutorial or style they went with and have a look at that.

As for brush sets you need to head over to the resources area where there are loads of stuff to use. Again, the styles change so you need to browse through them to see if its any good.

If your after a specific tutorial for Photoshop then you can search the site for PS related material or use the keyword index in my sig which is somewhat out of date but still works for some links.