im short an need a stool to grab the bars lol, i position the stool about a foot back so when i drop down i dont trip on it...anyways my first rep gets the swinging motion going so whats been working for me is i stick my right foot out on the first rep...problem solved...evry once in awhile ill have to stick my foot out a lil to keep the swing in check during my set...also where gloves (u prolly r) and sqeeze the bar tight, dont relax your fingers like there hooks
anyways i see alot of people using that swinging motion, they have some term for that type of training, i cant think of it now but if you do a search on you tube "50 pull ups" i bet it would come up....