Is it black? If so, before the painting solution, maybe try Forever Black or Back to Black by Mothers. Just a thought as these products worked great on my faded out fenders on my 2004 TJ. Made the black look like new.
If you do decide to paint, preparation is key. Complete wash and dry, and wipe down with alcohol to remove any residual oils or grease. My concern in using spray paint, is that it may look blotchy and uneven. A body shop would probably do a perfect job with a semi gloss.