Wedge the protruding nail firmly between the claws on the back side of a claw hammer. If you're working with soft wood -- and you don't want to leave a mark from the pressure of the hammer -- place a washcloth between the head of the hammer and the surface of the wood. Rotate the handle of the hammer to pull the nail out of the wood.
If you cannot apply enough pressure to remove the nail using a claw hammer, you can cut off the protruding head of the nail, using a hacksaw. A saw designed to cut wood will not suffice. Saw carefully back and forth against the nail, as close to the surface of the wood as possible. Keep fingers away from the blade.
You can remove a fully driven nail, if you can access the other side of the wood. Strike the sharp end of the nail -- on the other side of the wood -- with the hammer several times, until the head of the nail protrudes enough to be removed using the claw. Then follow the instructions from Step 1.
Fill holes left by nails with wood filler. Squeeze a small amount of filler into the hole. Lightly smooth the wet filler on the surface using a putty knife. Leave the wood filler to dry for at least 15 minutes.
Smooth the dried wood filler with sandpaper, until the surface is flush.
Douse a washcloth with rubbing alcohol or glue thinner, and apply the cloth lightly to the glue stain. Don't pour the liquid directly onto the wood. Excess rubbing alcohol may damage the stain or varnish of the wood.
Brush the stain with a toothbrush until the glue begins to flake off. Remove the flakes with a cloth.
For more persistent stains, slide a scraper along the surface of the wood, against the adhesive buildup, until it chips off. Using a scraper may scratch the surface of the wood.