uhm there's a couple things I'll provide advice from, I'm not too high in rank (though at some point I reached platinum) but I've been playing for almost 8 years now
Laning, Ashe has one of the longest autoattack ranges in the whole game, beaten only by cait and situationally by others with skills and whatnot, more importantly is that Ashe has more than her auto range on her W...
As an ADC your strongest point of defense is range, as long as you are attacking from distance you'll be doing a good job
Ashe's W also has multiple arrows and somewhat low mana cost, this means that if you time it correctly you can farm with W and poke at the same time, yes Cait has more range than you do but if you poke through minions with your W, you'll win trades and farm better than her... it's a bit complicated but the flow on trades is incredibly variable and you need to adjust on the fly, the most important thing to have in mind is that every trade should be worth it, meaning that if you stop and autoattack it's only because your opponent will end up with less life than you do, if that's not the case, keep running.
The lane flow is a bit more advanced but if you control it properly it can play in your advantage, basically, if you got no vision you're better under turret so don't push, freeze... if the enemy leaves the lane and you have the proper wards in place, push hard and make them loose minions to turret... everything is very situational though and again, you need to adjust on the fly, adjusting is what makes people rise in rank or sink
Mid game
If your turret falls down, the best thing a support can do is leave lane, this is because you're probably behind in both minions and experience, when the support leaves you earn more experience plus the enemy must be out of position to keep pushing, the jungler should pay special attention to the lane that is pushing against the most, though it's not always the case, again, adjusting on the fly.
Your best bet is to stay and farm as much as possible in order to close the gap in gold and experience between you and your enemy ADC, of course, if you farm it super fast the lane will push and you'll be the one out of position, your best bet is to freeze... or to push really hard and move to another lane... it all depends
You buy boots as soon as you can during early game but never before staying toe to toe with the enemy's dmg potential, not just from the enemy ADC but from the jungler too, more damage and less movement speed can turn ganks into kills for your team, escaping isn't always the right choice... Ideally you buy boots as your second item though
Late game
BotRK is good on every ADC but Ashe has special synergy with Critical chance, read her passive carefully and you'll realize that while BotRK is good, crit chance is almost staple on ashe, so if you rush BotRK, go for an Infinity edge right after and then a Hurricane, these are Ashe's current core items but it always changes... adapt
Teamfights with Ashe are complicated, you MUST stay out of range and you must know how to orbwalk properly... that said Ashe has 2 modes for teamfights both being always long ranged:
No life steal: do not make plays, catch people with your arrow if anything but don't run towards ANYONE, stay iout of the enemy's range always, stack your Q, poke with W and wait for the right chance to unleash Q
Lifesteal + hurricane: if there's more than 3 units in front of you and you have your Q charged up, turn that thing on and don't even move, Ashe can lifesteal a LOT from Q alone, of course always be mindful of your positioning and if needed orbwalk to safety but more often than not you can simply stand still and kill everything... until your Q runs out of course lol
