I have had great results working one bodypart/day/week. That is my favorite way to strength train and seems to really work for my body type. ( I don't build muscle very easily, either.)
The trick though is that you totally have to focus and work hard on that bodypart that day. No slacking, because you won't be hitting it for another week! The good thing is that because you are only working that 1 bodypart that day, you end up being able to focus better on it...as opposed to having to concentrate on 2 or more bodyparts in your workout.
Take care, Lynn M.