It's pretty simple stuff where locals work for $10 per day, your labour contribution is only $10 per day for unskilled labour. IE helping orphans, cute animals, quick bouts of teaching etc

As a libertarian I'm big on spending heaps of money on localised products(With low resource costs) while visiting these countries instead, I make an effort to do stuff that normally I might be stingy on. I figure the money trickles through the economy while encouraging local business.

I also donate because it also has relevance, but if you want to help a community while having a great experience, just pay for it.