aela in the companions guild can train you in archery, getting a bow to do alot of damage you need to craft one yourself and upgrade it to legendary then enchant it with something. i've got an ebony bow that does 150ish damage w/out any enchantments. takes time but its well worth it. the sneak attacks do help ALOT especially after you get the 3x sneak attack bonus. once you have that, plus a beefed up bow you can take down trolls one shot, hell, i killed a dragon with one shot! it was a base dragon, plus sneak attack, so it wouldnt have been hard to kill in the first place, but still, one shot!?