I would recommend a look at Adrians Smiths Facebook page if you like watching artistic process. He has a watercolour of a warrior character shown in various stages of progress with some explanation of whats going on. Also worth reading the comments to find out more.
Stage 1 - Pencil -- Facebook Link
Stage 2 - Underpainting -- Facebook Link
Stage 3 - Build Up -- Facebook Link
Stage 4 - More Build Up -- Facebook Link
Stage 5 - Finished Piece -- Facebook Link
I cant recommend this Facebook Page enough, new drawings from a great artist everyday!! Get on.