A T Wrench set, Standard and Metric. Allen wrenches suck ass, they hurt my fingers and can never get a good turn on the screws. T wrenches give you something you can actually use without hurting your hand.

Furniture slides. They have two types one for use on carpeted floors and one for hardwood floors. It makes moving furniture around so much easier.

I also keep a furniture jack. That makes it easier to lift up the furniture to put the slides in place.

Put a battery operated water alarm in the pan your hot water heater sits in, and change the batteries when you change out your smoke alarm batteries (whenever there is a clock change). TRUST ME DO THIS