First up, John Shearin sprays WD-40 oil on the blades of my barely usable pruners, then rubs them with #1 steel wool. The oil works to remove plant sap that gets on the blades every time they're used and over time, really build up.
After wiping the blades with a cloth to remove the oil, the pruner is ready for sharpening.
For more info: http://blog.behnkes.com/how-to-clean-...