Just to add to what he said above. When you clean it, use a degreaser or do like I did, scrub it w/an SOS pad rinse it off, then wash it w/dish soap. Mine was in pretty bad shape, the paint was peeling and stuff so I had to do alot of sanding. I sanded it down so much that there is no more texture to it. It takes some time, but if your paint is peeling, your gonna need to do it. After sanding it, go back to the sink and wash it again w/dish detergent. The reason I say use dish detergent is because it is a good degreaser. After this final wash, I let it air dry, using papertowels would cause unwanted lint on the cover.

Once it dried I masked off the parts I didn't want painted. Using masking tape I masked off each spark plug opening, the top of the oil fill opening and the port that goes from the valve cover to the intake(or throttle body, I forget). For the lettering I used this stuff called Liquid Mask. It's for model builders(like myself) and can be found at any hobby shop that sells plastic scale models. I brushed it on the lettering, being carefull not to get any of it anywhere but the top of the lettering. Let that dry. Once it's dry you can spray on a coat of primer. The primer will show any defects there may be like peeling paint. Let that dry and sand as needed. Wash again w/dish detergent and let air dry. Then put on another coat of primer. After that dries, you can spray on your color now. I'd suggest multiple light coats over a single heavy coat. I did 3 coats myself, followed by 3 coats of clear.

If you have any more question, hit me up.