The board itself should be a soft top board rather than fiber glass or epoxy that humans prefer. They are the best for learning kids and dogs alike. In fact, in most competitions they only allow a soft top board.
Another thing to look at is traction treads to add to the top of the board so the dog's pads don't slip off
The whole point is for your pet to have loads of fun, not wipe out every time he tries to stand up; just like when a daddy lets go of the bike as his daughter learns to ride.