Dada Vedaprajinananda looks at this question from the yogic perspective.  If God is perfect, then he knows what we need before we even ask it, so according to Shrii Shrii Anandamurti we should not ask for things.  If we ask for anything, then we should ask God to guide our intellect onto the correct path of good and benevolence. The ancient Gayatri Mantra is a prayer of this type.