If you pick to follow Hadvar when escaping Helgen. Once you are in his uncles cabin go through the dialogue. Once Alvor leaves the little girl and wife should go downstairs. (not that it matters).

You can sneak behind Hadvar and hit him to rank up your skills. He doesn't die he just gets knocked down. And don't hit to many times repeatedly or he will get mad.

I got up to 100 sneak trying this and lvl 17 before even leaving the cabin....