I'm also careful not to press the paper against the edges of my drawing board - if I'm really concerned about this, with a piece that will hang over the bottom of the board while I'm working in it, I may pad the edges of the board.
(The foam insulation for plumbing pipes is perfect for this - just slide a piece onto the bottom of your board.
The family tree I've just been adding to has, in the past, been quite badly creased, which is a shame as such a lot of work went into creating the piece. I thought about trying to remove some of them, but decided that I risked making matters worse, and as the customer hadn't mentioned them, I might just be drawing attention to something she wasn't concerned about!
(Keep your obsessions to yourself, Janet!)