To stop terminal screws working loose, put a small spot of oil-based gloss paint on the threads. The stickier the paint the better; emulsion paint will not work.
Power tools are aged faster by neglect, dust and damp than by use, so when they are not being used, wrap them in absorbent material and store them in a dry cupboard.
When changing attachments to a power drill, always disconnect it from the power supply; however careful you are, there is always the chance of accidentally switching the drill on.
When working with power tools out of doors wear rubber boots to give some protection against accidental cutting of the power supply cable, failure of the tool insulation and so on.