I just managed to bought The Techniques of Dylan Cole 3 Advanced Digital Matte Painting for some bucks at ebay :) Unfortunately part 1 wasn't available there. But I will practise with part3 then :)
It's got a nice flow to it, but if you're serious about getting into digital landscape painting you really should be starting with colors (atmospheric perspective) and a solid perspective like n88tr said. Just going off on a whim and painting is fun, but you may run out of steam and not pick up much on the way. Tutorials…