What is a do it yourself solution to resurfacing a flat top grill and what is the best way to clean one?

I have a Flat top Grill/Griddle about 4ft. by 5ft. it has some minor groves in it how could i do a minor resurface job to it myself without getting it professionally done and what would be the best way to clean it to have that "Brand new" nice and silver look to it???