Generic build

GAMEPLAY AND THOUGHT PROCESS
This build focuses on last hitting (massing levels on hawk shot to increase gold gain), really you need to constantly get creeps until you have the build up to an infinity edge, then you can pretty much kill anyone if your good at last hitting with the exception of a fed middle, not your problem though. The 3 doran blades give you optimal lane phase especially if your support is not good. Increased hawkshot levels will help you secure dragon and help you against ganks if used frequently when you have that "I think I'm about to take it up the ***" feeling. I'm against massing levels in volley because your build isn't focused on increased volley damage, its focused on criticals and attack speed/movement speed/ slowing to shorten the gap of enemy survival. When your level 6 I recommend wasting your arrow (if you think it could lead to a kill) because the time of the cool down is insignificant early game. Late/Mid game it's the initiator on your team, use it wisely and try to hit the person hindering your team the most in the fights.

MORE ABOUT LANING
The lane phase for this ashe is the most important part be assured, failing is not an option with ashe or this build. Remember 15/16 creeps is roughly a kill. If you add hawk shot gold onto this you get it down to roughly 12, which makes it a big difference if you have 150 creeps by 25 minutes. Kills are important if your jungler comes but do not lose a death to the enemy. You won't be a real threat unlike graves or vayne early game. Because of this people will underestimate you when you pull an infinity edge out of your cloak and start shooting elephants off your bow. With that Said I want to go to laning specifics.

LANING SPECIFICS
-Last hit
-Use hawk shot if you question your safety ( this will help you get more lane aware)
-Use ulti if you don't foresee your self using it in the near future
-If your a new disregard above and just spam it as soon as it comes up until you realize when it good to use it.
-Flash is to get away and ghost is to chase; these can be changed for the situation, but ghost is used offensively in this situation not defensively.
-Volley can be spammed, but make sure its not hindering. (creeps are more important do not **** up your last hits by hitting a volley fail on creeps!)
-Your support is your support, if they don't have your best interest in mind, "getting fed through creeps, not kills", do not engage in reckless behavior and miss creeps in the process!. Harass is important, but remember your goal is to last hit more and dont die, so only harass if you feel there will be no drawbacks to your goals.
-If you feel your going to be harassed, get doran shield in for one blade, this will give you health regen instead of life steal for durability.
-Don't die, Don't greed.
-Help secure/defend dragon, and make sure if your needed or your lane enemies disappear, provided you can make it in time go try and help, remember you have ghost and flash + speed boots so that you can get around fast.
-Tower diving is bad, unless you know 100% its a kill, or someone else tanks it.

WHEN YOU GET GOOD AT GETTING THE BUILD, OPTIMAL FIGHTING
Really the most optimal fighting with ashe is 1v1 kiting. With superior movement speed and slowing, ashe should literally be able to shoot and run a complete circle around the person before they can get close enough to you. Use this advantage on melee heroes, hit then run back, hit again, etc. Remember if they are running they are not attacking you, and support heroes don't do much damage, except sona, because the gods just made her Q O-****ing-P. Teamfights, it is your job to initiate, and the tank to follow up. Do not go in and try to be a hero, or ***** when they target you. Its not your job to run into them face first.
Bushes are clouds of death and should only be walked into with vision, be careful.. good practice is to always have flash ready, but that comes down to your gameplay.

WHY SO MANY ITEMS?
The last 5 items on the build are really just things you should get based off the enemy team. Banshees veil is if you have a lot of stuns or a trophy mage on the enemy team, guardian's angel is if you are literally the only one on your team doing dps. If you get guardians definitly get blood thirster and another phantom dancer so you can stay alive indefinitly. Black cleaver is just an item I enjoy a lot, and I find if you get it after your first phantom it really destroys squishy people and helps to take down artificial tanks (such as junglers etc.). Another phantom dancer just takes your crits to a level where its not so much the luck of getting a crit, its the luck of not getting one?. Blood thirster heals, and will keep you alive. Most people like to get this item first, but I find dying with it hinders you early game because of the stacks, and gives the enemy team the option of shutting you down.

LAST WHISPER??
Last whisper is not mentioned here because for all extensive purposes the enemy team will probably not build armor for you until it is too late, If you feel the need for it, don't hesitate, but I try to get people to keep their minds off that item, because newbs mistaken its power when in all reality its just trying to put you up to your actual power level from your natural damage.

THE THING ABOUT ASHE
Really in all honesty other ad carries are better than ashe, but ashe is a gateway champ to teach you obedience in damage and not trying to get kills despite harass. You have to learn how to right click attack instead of hit and run tactics. Don't fret if you lose a game, if you died less and got more creeps then their ad carry, you quite literally did your job. And your team should blame someone else. Good luck learning AD carry and best of luck raping people with your frosty serrated arrows of death!