Step 3: Clean, plane and sand your wood pieces
Use your planer (if needed) to flatten any uneven areas of the base or table top prior to sanding.
Then using a block sander or an electric sander, sand the base and table top smooth. You don't have to sand it with multiple papers and make it really smooth. The varnish I recommend fills in a lot of areas.
If you have any rotted areas on your table top (like I did), simply chisel out the rotted material until you are left with strong wood and various holes. (See photos).