Though it may seem counterintuitive, washing off the blades of your tools after each day of use, and then drying them, is the best prevention to premature wear. Leaving soil (or sap in the case of cutting tools) on the blades is damaging.
A wire brush can help keep shovels clean, helping remove clods of built-up soil. With pruners, I use a "tuffy pad" or whatever those green pot-washing synthetic scrubby pads are (from the supermarket) with soap and water. Then I dry them and once dry, spray with WD-40 on occasion as well. With shovel blades, wiping oil (I use motor oil because it’s there in the garage) on occasion with a rag is a good corrosion-prevention tactic.
Wooden handles will appreciate oiling periodically with tung oil or boiled linseed oil. Ask at your building-supply store which product to use.