Don't autoattack just last hit and volley the enemie. Ashe is a very good carry so you should be able to kill minions easily. Im at 250 by time their top farmer is at 100. Ashe is a great last hitter.

Dorans works great on ashe. Boots of swiftness so they can't escape ashe. Infinity for damage and a phatom to crit along with armor reducer and lifesteal. And since someone like rammus can taunt you for an easy kill banshees vail stops that.