A few:
1) Don't fix things that aren't broken; you often make things worse...
2) Put a white towel down inside the cabinet when you're working. It makes it much, much easier to find dropped parts.
3) Use magnetic nut drivers, because as you drop screws, they fall into spots you cannot see, and short out circuits.
4) Take the balls out of the game when you raise the playfield.
5) Don't use cheap tools, especially screwdrivers. Good screwdrivers are worth their weight in gold. Cheap screwdrivers strip screw heads.
6) The answer is usually simpler than you think. Don't make life hard, start with the simple stuff first, rather than shotgunning.
Marc
