Attacking and boarding a smuggler's vessel usually yields a specialist Carpenter, Sail maker, etc.
More Money when Dividing the Plunder
Sell everything you have except for the flagship you want to keep. This lowers your crew, which in turns raises your "share" of the Loot
When choosing ammo type select the chain balls. Then, directly after firing, click round balls and you will fire both of these ammo types in the same shot.
Get Rank of Duke With All Nations
Simply attack a town and defeat all of the enemys soldiers, then place a governor in charge, visit him and you will be promoted. Then leave the town and immediately attack it again and install a different governor, this will have the effect of making that nation very happy and promoting you up a level. Simply repeat the process until you a a Duke with every nation. It also has the added bonus of increasing the amount of land that you own. Just make sure you have enough troops to begin with.