well i would actually go for the 219 brush, but i guess it all depends on what kind of look your going for...i normally smoke out my shadow on the bottom so i use a brush thats a lil thick...but if you want a thin line then i would say line it as best as you can and then juSs grab a q-tip and straighten out the line and make it however thin you want with that..hope that helps a lil bit? sorry if it didnt haha my explanations arent very good..but pretty much its juSs practice makes perfect, experiment with what works for you and what look your going for...good luck!