Correct hull prep for new graphic???

[1955 classic]

Can anyone suggest the correct way to prep the side of a hull for a new graphic, obviously a good clean and removing the old graphic is the easy part. Then cleaners or buffers??? ( doesn't seem to be faded gel coat).
Removing standard 220 graphic and have new Griffen graphic and lettering from a PN member
Main worry is removing all contaminants so new graphic will adhere properly.

[shag]

I have always had goo luck with using rubbing alcohol on a clean cloth - rub the entire area well. Then use a vinyl squeegee to help get out any small air bubbles after application.