First step is choose the fisherman, he's got enough money and that extra food is really good. Step two is get the sloop. Then go to the store and fill up on harpoons and then as much luxory as you can, don't buy food or or anything else. Step 3 is fish the minute you start to get some food. Due to the fact that food may spoil only get as much as 200 fish per fishing session, but always have atleast 100 because you can sell it to get more harpoons if you need. Set the rations to max for th enitre game, if you run low just fish. if you see another ship just flee, only approach if it is english and the flag looks pristine, if it is tattered then it is a fake. Now the final and most important tip. If you see fish in the water (little dark spots) fish when you are right on top of them, it gives you a different minigame where you can get a lot more.

Hopefully this helps you.