Turn off the gas shutoff valve on the gas supply line if the oven is connected to the gas line. Wait until the burner pilots burn out. This ensures all of the gas is out of the oven's gas lines.
Remove the burner grates from the top of the oven and then remove the racks from inside the oven.
Pull the knobs off the oven's control panel. The knobs usually slide on. In some cases, you will locate a setscrew threaded into the side of the knob. Loosen the setscrew with a screwdriver and pull off the knobs.
Spray the oven's shell and control panel with glass cleaner and wipe clean with a cotton rag. If the oven has a lot of baked on grease, mix 1 cup vinegar into 3 cups water in a spray bottle. Spray the solution onto the oven's shell and then wipe the oven clean. The acid in the vinegar will break up the grease.
Clean the knobs with soapy water or use the vinegar solution if they have a lot of grease buildup. Place the knobs back onto the oven.
Raise the stovetop, if possible, and clean the area under the burners. If you cannot raise the top, reach down as best you can and clean the area around the burners. In addition, clean the burners as well. Use soapy water or the vinegar solution.
Inspect the holes in the burners. If they are clogged, ream them out with a metal pin.
Spray the inside of the oven with a quality oven cleaner. In most cases, you must leave the cleaner in the oven for a few hours.
Wait the amount of time specified on the cleaner, then wipe the inside of the oven clean with paper towels. Make sure you wear rubber gloves to protect your skin from the cleaner.
Clean the grates and the racks with hot soapy water and a scrub brush. Dry them off with a towel and place them back onto the oven.