Also when snading larger flat surfaces, I like to use a cross hatch pattern. For example; if you are sanding a wing, take your sanding bar at about a 30 degree angle stroke to the leading/trailing edge from tip to root then come back from root to tip with the opposite 30 degree angle making a cross hatch patern. Remember to not force the sand paper onto the wood and take material in small amounts as it is a lot easier to take more off then to put it back. This technique is one I learned doing body work on my old Mustangs and the results are such that after paint no one can tell I had to do any work in that area.