Contour sanding grips are great, but to get the most out of them, switch from sand paper to the 3M sanding medium. Very flexible, and you don't have to make a lot of passes to get smooth results. I use this stuff constantly on picture frames and it really works far better than paper--there is something very sepcial about the grit on this. I never have to sand down much finer than 220 with it, vs 320 with paper. Try it with a coutour grip. Really easy to hold in place. Here's a picture to help you find it.
The more I do, the less I accomplish.