I had a 1/8 inch stick the other night which I needed to make just a bit smaller to fit in a tight spot for a filler. I had cut it to length first and had a problem holding it so I could sand it. I discovered by accident if I laid it on a piece of sandpaper OF A COURSER GRIT than on my sanding block the stick stayed in place with nothing else holding it. I had so much fun with it, I had to cut a new piece and start over!
Have you ever wanted to sand something flush with out sanding the material it is attached to? For instance, after gluing on a wing tip you don't want to sand the sheeting. Apply a strip of duct tape or masking tape to one end of your sanding block. Just cover a couple of inches of one end. The tape rides on the sheeting and no sanding action takes place on that end. You can sand to your hearts content, right down to very close or even flush without worry.
These tips may have been "discovered" before. But they are a first for me. I started the hobby back in "75". I guess I'm a late bloomer

Ken