I started after sanding away all paint I clean with alcohol then take and cover with dielectric grease give that a couple days then go over the whole thing with a glob of silicone my frame ground is still shiny under the silicone after 2 winters in Maine.
I use Noalox grease under the ring terminal. Under 3 bucks a tube at Home Depot.. It conducts electricity and stops corrosion. Seal over the connection with RTV after you grease it up.