Ashe is a good range dps.Shes basic atack,volley and ulti cause a lot of damage and slow or stun(ulti stun).
Early game:Ashe cause a lot of damage with voley and frost shot and stun.You must atack other people with voley and carry of your mana.When you dont have much mana just rather stay near the turret and feed yourself.Ase in early game have very often problems with mana !!!
Mid game:Its difficult moment for Ashe before it buy a bloodthirster.Before you get it you must rather feed on minions and i if you may gank.
Late game:Ashe is very difficult oponent in this moment.She deals a lot of damage with voley and basic atack and she slows.She have ulti wich deals 600 damage stun and have very big range.She is very good in this moment for ganks and for team fights.She can also take frags with ulti :D.