Add a knob of butter to the cooking water from the potatoes, not all boils over. Put the salt then at the last minute in. To enhance the flavor of old potatoes is sometimes added a small spoonful of sugar to the cooking water. Do you cook the potatoes in their skins, let them even "scare" in cold water when they are cooked. The shell is then easier to make. Shelling wrinkly potatoes is a lot better if you leave them in advance even in cold water. If you make a potato salad, put the potatoes in boiling water and let them not be completely cooked. Add the dressing to the salad as the potatoes have cooled down completely, to infuse better the flavor of the dressing. Do you want crispy roast potatoes, sprinkle them over halfway through baking with a little flour.