I started on the interior - I pulled everything out of the interior, dash included, and the cardboard heater vents (at the kick panels) that ran from the firewall into the doors (so the back seat could be heated) via the kick panels and proceeded to wire brush, sand and clean in prep for the Lizardskin on the interior --- when it was reasonably clean, I sprayed floor, firewall, doors, package tray, trunk and roof with epoxy sealer first.