Things I have tried:
Selling my body: great idea but then I found out they wanted to cut it up and use the parts
Dumpster Diving: Worked Great in the US where people throw good stuff away, Have 39 orange life vest that dont float for sale if anyone needs them.
Piracy: After I said this in a barside marina, I now have a 110 foot Coast Guard cutter that follows me everywhere, so made some money selling the liferaft and epirb.
Local tourist guide in foriegn countries: Worked great until people started asking for things that wasnt in the hotel guide books
Pet sitting for cruisers: Great business if you can get the boats ever to come back for thier cute little kittens, by the way have 57 cats that need a home.