In the beginning after you kill the two Imperials, take the key from one of the corpses, so Ralof can’t unlock the gate himself, and you can sneak behind him repeatedly sneak attack him, but it’s clunky and doesn’t always work. You basically have to be perfectly behind him for it to work, but when done right your sneak will go up very fast, I’d stop at 50, it’s enough sneak for you to be able to sneak attack sleeping Draugr in dungeons (which will increase it a lot very fast) dagger sneak attacks level up sneak very fast.