When playing Ashe support the best way to get maximum value is by auto attacking as much as possible, whenever possible(when it's safe to trade auto's) in the laning phase. Mixed with constantly using W to apply Arcane comet and to also get the manaflow band proc.
If you cannot or do not poke the enemy enough early on, there's a very high chance the enemy will all-in your adc or you at lvl 2 or 3.

The wonderful thing about poking with auto's is the slow applied. which lets your adc poke as well.

At level 2 it's good to go hawk shot. Shoot the bird in a line from the bot lane through the enemy jungle to either the gromp on the blue side or the krugs on the red side. This ability is not only useful to make sure there are no ganks happening at the bot lane but ALSO let's your whole team know where the enemy jungler is. So then they can play safe if needed.

gets vision if you think the enemy is doing drake or baron's as well.

Hopefully by the time you and your adc are ready to back you should most probably have at most 800 gold. The first 2 items to buy are one long sword, and boots of speed with a pink ward.
On the 2nd back i prefer upgrading my boots to ionian boots and if i had enough money i would buy a ruby crystal as well.
Getting the completed boots is good for the cdr to spam your W more. As the damage you deal with your W falls of at lvl 4-7 during the lanning phase. the long sword helps up the damage.

This is the part that is so much fun to play. The whole point of this build is to reduce your ult cdr to 34 sec. Maybe even more if you get the drakes that give cooldown reduction. You get cdr upto 27 sec. So ult away and try to land the arrow during team fights.

Black cleaver : The main reason i prefer getting this item is for the 20% cdr. Also you can apply the on-hit effect of black cleaver with your W. ALSO your arcane comet applies a stack of black cleaver as well. With your W at a 2 sec cdr spamming W over and over starts to break the enemy little by little.

Liandry's : mainly a good buy to cause the burn dmg during, before and after teamfights to slowly wittle down the enemies health.

executioner's calling : right after i get black cleaver i look to see if the enemy has more than one tank. If yes - i buy executioner's calling to help apply the grievous wounds with your W. After getting executioner's you can get a liandry's and complete the item into a mortal reminder.