Some parents in my workshops find it helpful to make a list of the non-negotiable rules in their house, and to post it on the refrigerator as a visual reminder. Try not to make impulsive threats or bribes. When we're furious, exhausted or stressed out, we sometimes make threats that we're not likely to carry out. When you feel like you're about to lose your cool, try taking an adult time out. Shower your children with time, not material things.
Most kids have too many toys, anyway.
Remember that the best gifts you can give your children are those occasional moments of your undivided attention.