You are the AD carry, so you will of course be in bottom lane. This means that you will be against a support and another AD carry.
With this in mind, armour glyphs are a pretty good idea! A lot of lazy AD carries will just use flat or per level MR glyphs, but you are the damage dealer and early game you dont do any magic damage, so by taking armour glyphs AND seal, you will take less damage from the enemy lane.

In terms of masteries, pretty standard AD carry masteries. I choose to ignore the flash mastery, but you can take it if you like, just take one point out of the extra MR and chuck it in.

For summoner spells, I used to take Ghost and Exhaust, but lately I've been taking Flash and Ignite. Seriously, Flash/Ignite is OP!

Boots or Dorans?
Boots is always better than dorans guys. You dont need to do any math to figure that out.
What is the point in having 10 more damage when you dont have the speed to get off that extra shot?
That is why I start with boots. Trust, it's always better ;)

Try to stay in lane until you have a good chunk of gold. Basically, if you save enough for a BF sword, get it first priority!
Otherwise, get a pickaxe.
If you end up going b or dying with less than 975g, just finish your boots of swiftness, the MS increase is still worth it for early game lane domination.
Which brings me to another point..

Boots of Swiftness vs Beserkers Greaves
Well, I always take boots of swiftness on every AD ranged carry, especially Ashe. People who take beserkers greaves will argue that your attack speed will suffer early. The problem is that most of your attacks will involve you chasing or getting chased and kiting them. The extra MS from boots of swiftness is too valuable to pass up.
It allows you to get in range to land your auto attacks even when theyre running away.
It allows you to get away from their ganks where otherwise you would get caught and die.

After your boots and BF sword, youll want to get some lifesteal for lane sustain, and then you have a CHOICE.. rush a zeal or go straight for Infinity Edge.
Personally I go straight for Infinity Edge and I usually find myself staying in lane for a long time so I have a lot of gold when I do go back.
The advantages of getting a zeal are pretty decent though, the extra MS and AS are good for beign really aggressive. It sort of depends on who you're laning with and against.
The rest of the item build is pretty standard, early GA lets you be aggressive without consequence. The last thing to debate is...

Why two Phantom Dancers?
By now you may have realised that I'm sort of an MS freak. Mobility wins the games! ;)
Two phantom dancers + your boots gives you an ungodly amount of speed.
IE + two PDs nearly maxes your Crit Chance
Two PDs gives you about 2 AS, meaning more pew pew in teamfights.
Two Phantom Dancers is superior!

If you miss minions, you're ******ed. Please last hit every single creep, or it will take significantly longer to get to your final form, dominatrix Ashe.
Seriously, 200 minion kills is not that hard to get in 25 to 30 minutes. The only reason you should not be around that is if you are getting a lot of champion kills, which is ok but remember that two waves of minions is worth one champion! So prioritize last hitting over being a douchebag to th enemy.

Thats all folks, I've kept this as short as possible only explaining the important parts. I hope you follow this build to success, because as long as you're not ******ed, it's impossible not to dominate with it.
Just remember not to be dumb in the start, stay in lane as long as possible and last hit EVERY minion.
xMaYHeM.