Rub salt and pepper and other seasonings you want, into the roast. Thinly slice onions and lay on top of roast. Put in the crockpot with 2-3 cups water and turn on low if you are gone all day. It will be nice and juicy.
Put the roast in the crock pot with vegetables such as carrots and potatoes if you like. Fill with beef broth/wine/beer to cover the roast. Turn it on and leave.