1. Always wear safety glasses. You only have 2 eyes, and they are not easily replaced.
2. Keep your arms and legs out of the way. If cutting or drilling with a tool, keep your hands out of the way. If the knife or drill slips, it's going to cut you. One tip to add is when using an "impact drill", the drivers with a sleeve are the smartest way to drive screws. That will ensure the drill does not fall off the screw head and stab your hand.
3. Always unplug power tools prior to changing a blade.
4. Never cut or drill blind. Find out who or what is on the other side of the wall first!
5. Don't overextend your reach with a ladder. This is one of the most common ways people get hurt doing projects around the home. Solid ground, correct weight rating, and common sense goes a long way.