Ashe might seem pretty squishy adc but she has best lvl 1 trades (except if its draven). Her passive makes her deal huge damage from attacks. If you can try to land minimum 2AA on enemy. Not only he wont be really able to escape from you, he's gonna lose lots of health. Also try to find openings in enemy way of farming. Attack him while he tries to last hit minions (for some its basic knowledge but in lower elo its not).
Even if ashe is squishy you should play agressive and its good if you have agressive support like brand or morgana. If you can dodge good or enemies dont have any CC- just attack them, make them suffer for underestimating Ashe.
You should also watch map often to look for opportunity to help your team with E or R. Its really helpful.
Since you are playing adc, laet game might be tough especially if enemy has good assasin that wont be caught by you (yes you can literally 1v1 most of the assasins when you hit them with R). Besides this just try to stay with tank and attack the closest enemy to you Also if its possible try to R somebody you need to focus. The only exception is when you are about to get killed and your ult will save you.