One of the things I used to do for customers in the past is help them set up an internet connection. This was in the time of 56k modems and floppy disks. Not everyone had a CD drive. It was pretty simple, and often other issues would crop up as well.
One day I got a call from the ISP that I would often refer customers to. They had better customer service and rates so it was an easy decision. They said that one of their customers got a virus from using IRC and did I know anything about it? Actually I did, because I had gotten the same virus recently myself and it took some time to figure it out.
So I gave the solution to the ISP and then later asked what happened. They said that my solution had worked and their customer was very happy. Now of course they could have told the customer about me and I could have done the job and gotten paid. Sometimes though the relationship is more important than the money you might make. By doing that for them I showed that I appreciated what they had done for me. What did they do for me? They helped me if I had a problem with setup that I didn’t know how to solve. Ensuring that I had a happy customer.
It doesn’t matter who gets the credit, the money, or your time, but the most important thing to be concerned about is the relationship that you form. Sometimes the money doesn’t come at first, but eventually the rewards always appear.