Wipe it Dry
It's most effective to use microfiber towels, but you can use old rags if you wish. Wipe everything as dry as you can. Areas you can't reach can be left to air dry.
You may still find some dirty spots. You can use the towel on these and scrub those areas clean with a little "elbow grease."
Spray on Some Protection
Spray down non-metal areas with plastic/vinyl care spray. A popular brand to use is Armour All. Leave it settle for a couple of minutes, then wipe off excess.
Using a microfiber towel or other soft cloth, buff the protectant to a nice shine. This will not only protect your plastic and vinyl coverings from drying out and cracking, it will also make it look quite nice.
Remove Protective Plastic
Now that you're finished cleaning, drying, and buffing, you will want to make sure you remove the plastic saran wrap or plastic wrap you used to protect your electrical components. If you forget, the heat from your engine will melt it on, which is definitely something you don't want to have happen.