Just a note: if your valve cover is warped, it will leak no matter how hard you try to seal it. Once you get it off, lay it on a flat surface & see whether it is warped.
A gasket scraper is very handy for getting the old RTV seal off. Scrapers are available at www.summitracing.com
but I think they should be available at places like Autozone . . . maybe.
I replaced the RTV seal on mine TWICE & it still leaked (b/c I was impatient, didn't let it set up long enough, & then didn't let it dry long enough). So I finally had the mechanic do it. He used both a gasket of some kind as well as the RTV sealant. Now no leaks (well, I also had to have the oil filter housing re-sealed w/new O-rings, & had to have my rear main oil seal replaced, then I had no more leaks).