I have found the more pieces of driftwood and rocks you have to work with and choose from, the easier it is to create a good looking aquascape. I would definitely recommend picking up more driftwood as your very limited with only a single piece. I would start walking creek and river banks and just making a stockpile...
I really like the look of driftwood entering the water from the surface, instead of just having a bunch of pieces resting on the bottom. Here's a perfect example of what I would like to re-create once I collect enough interesting pieces:
http://www.youtube.com/watch?v=MVknMkdD2bI&feature=related