Gear should be inspected before and after each use, according to the manufacturers’ directions. Pay particular attention to cracks on surfaces of ascenders, sharp edges on cams, worn places in harnesses, and cuts in rope.
Use a notebook to safely store the directions on how to use and inspect every piece of gear that you own. Use a calendar to keep up with when the gear went into service – and follow the manufacturers' directions as to what to do with worn or shock-loaded gear, no matter how much or how little it is used.
Samson has released an excellent article on Rope Selection, Usage and Retirement and can be found here: PDF
An excellent resource for learning more about how to best inspect climbing equipment is the Petzl Web site, which you can link to by clicking here www.petzl.com. The site shows examples of damage to equipment, along with recommendations as to whether it should be monitored, repaired or replaced.
Here are some excellent PDFs for inspecting your gear from our friends at Petzl:
Protecting your Harnesses
If the decision is made to retire a piece of equipment, destroy it before disposing of it. That way, others won’t use it by mistake.