Flattening by Hand
Hand-sanding, planing, and scraping can be better than power sanding for certain applications.
With so many power sanders available these days, hand-sanding may seem anachronistic. But sanding by hand affords great control and allows you to smooth away the swirly scratches left by random orbit and vibrator sanders.
When sanding flat surfaces by hand with sheet sandpaper, use a suitable backer block. Many commercial sanding blocks are made from rubber, which is flat and rigid but which flexes enough to prevent the abrasive particles from breaking off prematurely. If you use wood sanding blocks, it’s wise to glue a layer of cork to one face for the same reason.
I often like to use garnet paper for hand-sanding because it has a unique “bite” that leaves a great finished surface. Hand-sanding is usually done with the grain, in which case it’s okay to skip intermediate grits. You can safely jump from 100-grit paper to 150-grit to 220-grit.