Choose one neutral trim paint for the entire house rather than buying a gallon of a particular color for each room and using only a fraction of each can.
Cost: You have to forgo the trendy color combos in the paint manufacturer brochures.
Savings: $50 on paint for three rooms.
Bonus: Crisp white trim is always in style, and you'll never have to rummage around for the right can for touch-ups.