With money you have buy some cannons, chainballs, and cannon balls that kills people also hire as many crew members as possible.
Chainballs destroy ships sails and also kill sailers. When the enemy ship is stoped board your sailers and capture the ships and sell them in other capital citys. When you have enough ships to distroy pirates and other ships make one to go around and find maps.
Lots of Money:
This will make you very rich. If you start out at Magarita on the tutorial, you will notice the high price of tobacco. Go to one of the other ports and buy as much tobacco as you can (as long as your buying price is less than 900;
usually they will buy it in Margarita for 1000). Then take it back to Margarita and sell it. Keep doing this until you have as much money as you want.
Around Grand Bahama there are lots of islands. Go into Andross and buy fish it sells good around the other islands. (I always use this and start in Grand Bahama).