Something you should invest in (if you already haven't) is a set of rasps and files. They'll save you so much time breaking down those rough spots and you have a lot more control than you would if you just used a palm/mouse sander. When you rough out your shapes with the rasps, you can move on to the files to really get your edges crisp and your surfaces smooth.
Here's a cheap set as an example.
Yup, I have one of those! I could seriously invest in some more, I can definitely imagine that I could more easily do with more different shapes and coarsenesses!