Threshes hook combo's with your slow is an easy way to get a kill early or late game.
Sokara Or Sona Are decent picks Since they both have heals, but you aren't that squishy.
Any other support is okay.
Pros / Cons
+Ashe's Q makes it easy to take towers.
+Ashe has a very strong ultimate, especially for picking off champs who might have got away.
+When you get your crits up, your slows last a lifetime.
+She has a very strong laning phase, and is great in team fights.
-Champions that have long range aren't as effected by your slows.
-Ashe's farming ability isn't as strong as other adc's like caytlin or twitch, until you build runanns's hurricane.