Step 1: Cleanse
Step 2: Mercury Treads
Step 3: Banshees Veil
Step 4: Quicksilver Sash
Step 5: ???
Step 6: Profit
If you didn't follow the following steps you are either
A: Gangplank or some other equally useless character
B: Incapable of devising a strategy.
Edit: I'm being mean, allow me to backtrack.
This game requires CC/support, that is true. It also requires a balanced team, If you want to play Gangplank, that's your prerogative. He does a lot of damage so I can see why anyone would want to be him. But if you are chosing Gangplank and your team has a lineup of Master Yi, Mordekaiser, Nidalee, and Corki, rest assured that your lack of CC is going to bite you in the ass and you WILL lose.
Any and every team should have the following
1 MASSIVE mellee dpser
1 MASSIVE ranged dpser
1 MASSIVE tank with CC
At least 1 Support with CC and defensive abilities
1 Mage Support with good CC and offensive abilities.
If any of the mellee/ranged/tanks have worthwhile CC (I.E. Ashe's stun/slow, Chogath's rupture/scream, Poppy's heroic charge, Shen/rammus's Taunt), then that's a bonus and will probably give you a better chance of winning.