Gangplank loves his booty! N....No... not that kind of booty... not HIS booty either, just... nevermind....
Make sure to last hit as many minions as you can with your Q, as the bonus gold can really add up. Try not to trade at all early game, as your mana pool can be fairly sensitive, and you need to save it for farming or clutch oranges when you get caught out by a stun. Make sure to max your Q first as it not only makes farming/poking easier, but it also gives you more bonus gold per kill. Another great thing about Gangplank's Q ability (Parrrley) is that it applies on-hit effects. This is why Rushing a Statikk Shiv on him, especially with this build, is such a great option. The early Avarice Blade boosts the amount of bonus gold you receive and cooldown boots will make it easier to farm exclusively with your Q (the cooldown boots also help out with poking early to late game and bringing your delicious oranges back quicker).

Also, make sure to keep your eye on mid and bot lane early, as your ultimate is global and can really make a difference in snowballing other lanes :)

BECAUSE HIS Q'S HURT!!!!!
By the time you reach full build you should easily have the largest critical strike in the game. Check the after match statistics for proof ;)
Your enemies will cower in fear when they see you coming at them! Also, most enemies can't catch you! Laugh away the pain as you stuff your face in Oranges and rally your team with "Raise Morale"! He's a great Champion as far as being about to dish out damage, catch up to enemies (as well as get away from, if you need to) and brings tons of Support to your team in the form of AoE and Auras!