I peel the corn all the way and remove all the silk, then brush it with a little melted butter and salt it lightly and then wrap it well in aluminun foil. Then I just throw it on the hot grill while while everything else is cooking. Be sure to have the lid of the grill closed to help it heat more evenly and turn it over every 5 minutes or so. I think we usually leave it on the grill for about 20-30 minutes total? I never have really timed it. If I'm not sure if it's done, I'll grab an ear using a good hot pad and squeeze it slightly -- if it gives in to the pressure, it's done; if not, it goes back on the grill!
My family thinks this is the best corn they've ever had!