Title caught your attention didn't it?

In essence, a good Gangplank is a Gangplank that crits. Alot. With the right items, Gangplank will and can destroy enemy teams.

Start with a Brawler's Glove, a Health Potion and a Mana Potion.

First trip back, turn your Brawler's Glove into a Avarice Blade and get normal boots if you can afford it.

Next, build for another Avarice blade before completing your boots. After that, build yet another Avarice blade. By then, your gold income should be very fast and not to mention your critical rate increasingly more common.

*Note, if you're being push hard or feel the need for more firepower, get a life scepter or sheen in between the 2nd and 3rd Avarice Blade.

Finally, start building your Phantom Dancer, this bad boy will allow you to outrun enemy champions and finally let you chase them down.

What? Not enough damage output? Don't worry, with 3 Avarice Blade and Greed Mastery, you'll have yourself a B.F. Sword in no time! Turn that into a Infinity Edge and you'll start really dominating the game. Usually the game end around this time or shortly after, but if you're having trouble chasing enemies down to kill them turn your Avarice Blade into a Youmuu's Ghostblade for extra movement speed and attack speed.

What? Match still going on?
Go ahead, sell one of those Avarice Blade and buy yourself a Bloodthirster. This will help you survive longer with lifesteal and is useful because by now your attack speed should be semi-fast from Raise Morale passive. Sell your last Avarice Blade and make yourself an Trinity Force if you are still fighting.

Self explanatory.

Marks for crits, Seals for mana regen and Gylphs to reduce cooldown. You will find yourself laning longer early game and being able to parrley/harrass your opponent. Don't forget that you get extra gold for killing an enemy minion with parrrley!

DENY!

Yes, League of Legends doesn't really have denying BUT with Raise Morale, you can kill your own creep to increase movement and attack speed. Use it often early game because one creep every wave makes a difference.

Remove Scurvy - what a nice skill to have, it acts like cleanse and heal summoner skill put together.

Parrrley!!! Your most used skill. This ranged attack will deal massive damage if you crit on the enemy so buy those Avarice Blades! Don't neglect building attack damage though since it does help increase the base damage output.