2H, HB, 2B, 4B 4B for dark cave like settings, 2H for defineing light, you can skech then use the eracer like a white pensil on grey paper, i just helps me to pretend that.
i persnaly havent tuchedd 4H yet
gum eracers, i spoted a "sand eraser" in a store. but, i think what your asking for is a kneelable eracer, thay say you can wash them.
also online i saw a colored set of them, if you want to pay for it.
also paper is the most important for an artist, beg tire is office coppy paper, don't fear balling them up and throwing them away.