Armorclad Epoxy Floor Coating
Garage Floor Coating, resurfacing painting and epoxy coatings - The solution to your garage renovation needs - Franchises also available
Garage Floor Paint | Epoxy Concrete Floor Coating | Basement Floor Paint
A few options. I've done this twice and had great, bulletproof results.
In one word:
CLEAN!!! Follow all the manufacturer's directions, but the job will only be as good as the surface underneath. If it's painted-remove every little speck. Grease spots? Degrease and degrease again. Other than that, it's just like painting any other surface, only flat!
I'll be doing this house, but only after I can find a way to get my wifes' junk out of the way.
God, I sure miss my 3 1/2 car garage I had in Wisconsin!
Another option I helped a friend with: Tile. If you shop around, you can find super low prices and get a beautiful floor that will last forever too. Just seal the grout lines 48 hours after you float the grout.