Summoner Spells:
Flash- I have no idea why some people would pick ghost over the ability to fly past a wall...
Teleport- This is an amazing spell that lets you teleport back to your turret at the beginning of the game so you don't miss out on even exp from one minion. The difference of having your ult 10 seconds earlier could make the difference between getting a kill or not. This is also pretty nice mid game or late game for backdooring.

Doran's blade really helps because Ashe is squishy as hell. Try to lane long enough to get 1k and go back to buy boots of swiftness.

Boots of Swiftness: Ashe runs slow as hell. That's why I chose to use that quintessence.

Bf Sword: Need to be able to do some damage.

Zeal: Attack speed is pretty nice for hitting a turret if you get the chance.

Cloak of Agility: Just what I chose over Pickaxe while you are getting Infinity Edge.

Phantom Dancers: The best item for attack speed and the 8% movement helps a lot.

Bloodthirsters: 2 of them. The damage and lifesteal help you hit hard as hell. If you get to the point of finishing 2 bloodthirsters with this build, you should be hitting 800-900s every shot that also SLOWS your enemy. You should be able to take down a tank in a matter of seconds.

Banshees Veil: Just to throw in some hp or def because as i mentioned before, Ashe is one of the squishiest characters in the game.

Armor Pen.- Helps you hit hard early game.
Speed- You can slow to get away from people, but it takes a while to get across the map.
Cdr- Spamming volley is pretty fun, effective, and it pisses people off.

Overall, Ashe is a stronger teemo that doesn't shroom. Your squishy as hell, but the damage you can put on your opponents can be devestating. If you can get a kill or two in early game without dying, chances are that you're pretty well off and you can feed off of anyone with 2k or less hp in about 5 seconds. Good luck with this ^-^