For best results, use starchy (as opposed to waxy) potatoes. Should you peel them before cutting? That is completely up to you. Skip peeling if you want to get the most nutrients from the vegetable, or don't if it sounds unpalatable to you. If serving to picky kids who have yet to be introduced to potato skin, know that, after pureeing, the potato skin becomes part of the mass and, therefore, quite invisible.