Depending if you have a major book store near by they often have a good selection of books on sci fi / fantasy mat painting etc. Do what I do and go find your self a quiet corner and browse a few. Don't get fooled by the glossy pictures,yes sure they look fab but some books are all pics and no solid techniques.

There's an awful lot of 'learn from the digital masters books' out there that look great but actually tell you very little at all. You don't want to end up spending a fortune on a book that's actually got barely a couple of vague lines in there on actual technique.Some books have a knack of looking the business until you get them home and then for some reason all that you thought was in there has mysteriously disappeared. Bitter experience of many moons ago speaking here!