For rust removal rub the part with aluminum foil dipped in vinegar.
Any decent magnet in a tin can will do for retaining small parts. Magnets can be removed from old speakers, magnetic items, or purchased from Radio Shack or hardware stores. A washer or large nut can be used to hold a magnet in a plastic or aluminum container.
When mixing epoxy etc mix it well and never scrape the mixing container or surface. The material next to the surface may not be mixed well or in the proper proportions.
Use anti-seize on any joint or surface between dissimilar materials.
Heat releases Loctite.
Silicone dielectric grease available in very small to large tubes from auto supply stores works well as a corrosion inhibitor and for waterproofing electrical connections. Dip the ends of wires in the grease before crimping them into connectors. It also works as a decent field lubricant.
Alcohol prep pads available at any drugstore work great to clean tubes before patching. They are easy to store in a tool kit.
Emery boards, the type used for nail files, work well for abrading the surface of tubes before patching.
Don't over inflate tubes while checking for leaks. They can stretch and fold inside the tire when reused. The wrinkles can rub and cause a flat.
Tire sealants will ruin the pencil type pressure gauges. They will also adhere a tube to a tire fairly well.
A piece of carpet under your work area can keep parts from escaping the area.
A simple piece of rope tied to a hook in a ceiling or rafter can be used to suspend a bike so it is easier to work on.
Small plastic zip-lock bags are great for keeping parts together. A Sharpie marker works well for labeling them.
When taking things apart take LOTS of pictures.