Sanding surfaces should include gradual sanding, starting with a 60-grit to 80-grit paper for solid wood and 120-grit paper for plywood, and finishing with a 220-grit paper.
Process/Skill Questions:
Why are there different grits for sandpaper?
What is the literal translation of "100-grit" sandpaper?
How does material determine the selection of sandpaper?