We will not discuss how to make money but we will cover our experience on how to get at your money in foreign ports.
Our first mistake was leaving the US without an American Express card. We have Visas and Master Cards and they are good for most things put American Express offers some unique features which are valuable for the traveling yachtsman. The 2 main services they provide are check cashing and Travelers Checks at their offices. They also give good exchanges rates to local currencies. They only have offices in major cities but Visa only partners with local banks and doesnt have check cashing or a break on Travelers Checks.
Travelers Checks are the best way to carry large sums of money onboard. They are safe, may be exchanged at any bank and banks give improved exchange rates for Travelers Checks over cash. It is important to carry enough cash or Travelers Checks to cover the bond when you enter French Polynesia because using a credit card will incur a hefty cash advance charge.
ATM machines are available on the larger islands of French Polynesia and in Rarotonga, Pago, Pago and Nukalofa but elsewhere you are stuck without cash or TCs. Travelers Checks are not accepted at most businesses but any bank will take them gladly for local currency. They should always be in US Dollar denominations.
A good supply of 1 dollar bills is helpful when trading money with fellow cruisers. All boats traveling in international waters carry US currency no matter where they are from. Many times you are leaving a country and want to sell the remainder of you money to a friendly cruiser but you need to make change. Ones are very useful. We keep a bunch in our abandon ship bag in case we get marooned and want some money for the bar.