All of this and more...
These are all great suggestions - foam brushes, thinning the varnish, not shaking the can.In addition, I'd reccommed applying the thinnest coat possible. Too often people try to slap on a thick coat, thinking the finish will build up faster. Unfotunately you get bubbles and crevaces. Your first two or three coats on bare wood should be cut with about 50 percent thinner. 4th and 5th should be cut with 25 percent thinner, and the last coats can go full strenght. While applying the varnish, stroke the brush in long movements. If you get bubbles, simply run the brush over them until they go away. After you have coated your peice, take your brush and run it over the wood again (without dipping it in the can), absorbing any globs or execessively wet spots. This should do you well. Make sure you get at least 10 coats on - more if you can!Rob