How should I prep for a color change over existing good paint?

Alright, alright, I won't shoot clear over the entire car. But yes, she's pretty easy on the eyes. Were very good friends--I wouldn't do this for just any old neighbor.

I finally had some time to get started. Wet sanded both pieces and primed the fender. Heading out of town this weekend and will try to get this buttoned up on Sunday. I appreciate the help so far, this ain't too difficult...yet.

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