I find I get the best results when I paint a board laying flat.
If I paint a board standing up, then the paint tends to drip down and form waves or bumps.
On the other hand, when I paint the board lying flat I can only paint one side at a time. If I paint the board standing up, I can paint both sides so it goes twice as fast.
Is the preferred method of painting to paint flat, or is there a way of painting a board standing up so that it doesn't drip? (this would be applicable to fences, for example).