How do affiliate programs work?

Trying to see if this might work for me. I'm guessing it works like this, i have a product or service and people will market it for me and i pay them for the sale or lead. But how do i get started, how to protect myself from getting scammed, etc.? Im looking for a better alternative to adwords...Can someone who does this kind of work please p.m. me so I can get an idea of where to even start.

Thanks,

Start at "search" button