General

i tried that once^ ended up getting 192 lol

Health potions.
Lots and lots of health potions.

lol thanks guys

Dude, none of these people are right. Ashe is an ADC and ADCs are all about speed. Get 6 boots of swiftness and you will be mvp of the team, no doubt.

Boots of Speed + 3 Potions
1-2 Dorans
Berserker Grieves
Vampiric Scepter
Infinity Edge (BF Sword first)
Phantom Dancers (Zeal first)
Last Whisper
Guardian Angel
The Bloodthirster

You should build almost all ADC like this. You can go BT first for some like Graves if you are doing well in lane. You'll just get IE later.
About getting BT and LW as 3rd damage item (it is completely viable to get GA after PD + IE): [url=http://www.reignofgaming.net/blogs/a-different-view/diff-the-ender/20875-the-bloodthirster-vs-last-whisper]Look Here[/url]. This doesn't apply to Corki or Vayne if you read the next article by the guy where apparently a next PD would be better.
Other viable options for defense item besides GA are QSS and Banshee's Veil.

Starting Doran's is okay but not recommended if it is not a sustain lane. Also the speed in the beginning really helps. The only time I don't start boots is when I'm trolling with a premade.

Uh~
I start with Boots and 3 pots, Some may argue to take a Dorans blade if you have a sustain support(Soraka) but i prefer to take boots and 3 pots to be on the safe side.
-On my first 'b'i get 2 doran blade or 1 doran 1 dagger then a ward & pots.
-Berserker Greaves and Vampiric scepter
-BF sword
-Zeal
-Blood thirster
-Upgrade zeal to phantom dancer
-If im too squishy i get a guardian angel IF im doing well and carrying like i should i get an infinity edge IF the opponent are tanky as crap i get a Last whisper.
-^Get whatever you didn't in that step.

any build without boots of swiftness