Start with Brawlers Gloves and 2 pots, then you uppgrade it to zeal. When you have enough money you buy dagger and cloak of agility and then upgrade it to phantom dancer. After that you buy Ionian boots of lucidity. Continue with Vampiric Scepter and B.F. Sword and upgrade it to bloodthirster. After that you buy Infinity Edge. Then you can either buy Last whisper, if the enemy team starts buying armor, or you buy Madred´s bloodrazor. Finally you buy either frozen mallet if you die very fast and need the health, or if you want to slow the enemies. If you dont need Frozen mallet then you buy Black Cleaver. Thats the build i use when i play Gangplank and it works great. Good luck!