If you have the time and the money, look into velcro bondage cuffs. Just tie something to them and the bed, then use the cuffs on them - they can't get out, it can't get too tight, and it's easy for you to do and remove.
Otherwise, tie a bow, then pull one loop through. That leaves a knot with one loop which is easy to undo (just pull that loop through too). You do need to be more careful with the tightness on wrists and ankles though - if you can't get a finger between whatever and them, it's too tight. A pile of sites will give more clues.