While a planer will help you some, what you really need to start out with is a jointer. You will want to face the board on the jointer so it is truly flat, then run that board thru the planer. You can use a jointer to remove small amounts of twist and warp and wave, where as a planer will many times leave those in while producing a very nicely finished board WITH twist and warp and wave. How do I account for it, well just by judging each piece.
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