all in all, your runes are for early game survivability, as you will take significant harass when bullying your opponent out of lane. being able to stonewall enemy harass and punching through their defenses will give you a definite advantage when trading in the early game.

as quinn, you may not be getting the instakill burst that other assassins have, but your damage is far more consistent, and you want to keep it consistently high. you want all the damage you can get, and as your starting items are focused away from that, improving them will keep you alive long enough to continue do apply a hard but steady pressure in lane.

your build items should focus on having a global presence early on, then making that presence much more pronounced by the late game. unlike other assassins who might go for broke just to take out a single target, you want to have a consistently high damage throughout the fight, and the item's reflect this.

having berserker's greaves and a zephyr early will allow you to quickly go from your lane to any other point on the map, meaning you'll be able to help in any fight. this allows you to assist your entire team, rather then watching team mates fall behind and you have to carry the game alone.

after this building heavy damage and penetration through your trinity force and ghost blade, will give your global presence some astounding potency, quickly traveling between lanes and picking off anyone whom might be overextended.

your offensive items make this potency even more pronounced, either giving you even better mobility and vastly superior crit damage through the phantom dancer, target shred and additional sustain through the black cleaver, extremely potent burst through your infinity edge.

and finally, your defensive items allow you to live near the brink of death, charge through enemy fire, and take down high priority targets very quickly, either by returning damage back onto your attackers with thorn mail, escalating in power as the battle goes on with the maw, or shrugging off CC and returning the favor with heavy damage through the scimitar.

Q - this is your highest base damage ability, and one of your few forms of defense with the radial blind, but it isn't what gives Quinn her burst. this is great for preventing some damage during duels and as an execute for fleeing enemies, and should be maxed second.

W - this is by far Quinn's least useful ability, as the active gives better vision and can see into bushes, it's on such a ludicrous cooldown it's useless even when maxed. the passive attack speed it grants does help with assassinations though, so taking a point early will be very beneficial, but no more then that until you have everything else stacked.

E - this is assassin Quinn's bread and butter ability, and in some ways, makes her a more dangerous assassin then even Zed or Talon. her E acts as her initiation, her chase, her escape and her burst all in one, and being on a really low cooldown, can be used to keep up with enemies and continuously proc your passive and your trinity force, dealing in excess of half health on squishy targets, and giving your opponent no choice but to try and match your power. max this immediately, and use it as often as safely possible, especially after getting a trinity force.

R - as her ultimate, level it as soon as you can, whenever you can. due to it's massive bonus to movement speed, you can use this to join in, or mop up, nearly any fight on the map. you still use your abilities in the same way, just in melee range. while you can chase with ease, tower diving is not advisable, so using the burst from exiting your ult, and staying just out of tower range, you can still get kills even if the enemy makes it back to their tower.

while most marksman obtain their global presence through skills with incredibly high, or global range, quinn's global presence comes from her insane mobility. as a pro, she actually has much greater global presence then many other ranged champions, however this comes at the cost of her having to place herself in harm's way, where others can maintain their distance and strike from afar, without risk of retaliation.

the other side of her kit is her damage. while she is better suited as a top lane fighter or a mid lane assassin, she still gets the majority of her damage from her auto attacks, and is very similar to Ashe in that she lacks the plethora of high damage abilities of other champions in these roles. this leaves her trying to stay alive long enough in a fight so her opponent exhausts their damage, allowing her to counter attack swiftly and efficently.