Quin is a low range (525)/melee (as Valor) ADC perfect for defensive burst play, or depending on the support super agressive poke.

she fits well into most teamcomps, with a decent ammount of utility to skills and base burst (via harrier) that allows her to melt most of her opponents

the main drawbacks to Quin is her lower than average range for and adc, poor ad scaling on skills, and the fact that, while being forced into engages by the premise of her poor range, very little durability.

Runes I like to go AD marks, Armor Seals, scaling MR Glyph's and either Armor Pen or flat AD Quints

because harrier, her passive scales well with ad, and its her primary damage multiplier i find flat ad to work best, seeing as Armor pen is just about negated when we get her first damage item, The Blade Of The Ruined King. Being obliterated as necessary by the final build item of a Last Whisper.

Everything else is pretty standard and i feel is not necessary to explain.

I'm aware that more and more people are recommending the ranking of Heightened Senses. I myself tried this and found it to be, lackluster. though the increase in As is wonderful you lose out on a lot of dmg and chase potential with this plan. Keeping this in mind, i tend to get Heightened senses at level three, but max it second, as once the chase beings, more AS is ALWAYS a good thing. Blind is amazing as a utility, and that's why I grab it second, but scales poorly and has little other benefit.

now for her ultimate, tag team. we run the standard grab it when you can but whats more important then that is how you use it. obviously we love an AOE Garen style execution, but the bonus AS (80%) and movement speed are true clutch bonus's letting you engage from behind, get in and get a direct blind, Clean up fights, literally rip right through towers and run off, and in general provide outstanding mobility for chasing, fleeing, or split-pushing objectives. add a little life steal on that 80% bonus AS and you're golden.

just dont forget that after casting tag team, you cannot reactivate for skyfall until three seconds have passed, so if you have three people low and want to chase them down, cast tag team, follow for three seconds, use Vault to the furthest one away, and drop skyfall on them all as they try to peel you. easy triple kill.

This is fairly barebones guide, as im well aware, but i cannot build more into this until I myself know Quinn better, any comments Sudgestions and or questions will be appreciated, insofar as its not along of the lines of "you suck" and or "uninstall" Please remember this is a guide, not a "do it this way every time" though i have noted it works most of th time