Wash after each use. Make sure to always get all the soil off the tool, even if you have to use a screwdriver or larger tool to scrape it off.
Make sure your tools are dry before putting away. It’s a good idea to prevent rust and handle rot.
Sharpen cutting blades. A couple minutes with a sharpening stone will save lots of aggravation from a dull blade.
Clean any tools that have been used for chemical applications. Fertilizers and other chemicals can corrode metal parts quickly.