First, remove the access covers to the center tunnel, the plate on the front of the steering column and open the engin bay cover.
Second, put a large trash bag over the seat to keep it dry. A draw string leaf bag works great.
Third, remove anything large like sticks, twigs, leaves, etc... by hand.
Fourth, use a leaf blower to blow out as much as you can from everywhere.
Fifth, use a plastic putty knife to scrape the years of dirt and crud.
Sixth, use Simple Green Cleaner (WallMart, hardware stores, etc... carry it) mixed 50/50 with water in a spray bottle and soak it down. Give the greasy areas a real good soaking. Wait 5-10 minutes and hose it off.
Repeat steps 5 and 6 if needed.
Blow it off with the leaf blower when done.
Pay extra attention to the areas in the engine bay that you cannot see easily. Dirt and leaves tend to pile up under the engine and a leaf blower tends to blow it to the opposite end you are working on, but not out of the tub all-together. You have to dig it out by hand.
Then its time to greas all the fittings, check your center nut for tightness on the bottom of the lower articulation joint, grease the treadle if yours is a cable operated treadle, grease the ball joints, FEL joints, etc... with super lube spray.
If you don't have an owner's manual, call Terry at Power Trac and see if you can get one. It shows the lube points.