I've never offered to help someone and expect payment later. If I expect payment, they know upfront. When we put in propane, an acquaintance offered to do it (with me helping him). He told me what to purchase and to rent a pipe threader. When we got done, he asked for payment, including overtime rates because it was a Saturday. I paid him but a few weeks later when he wanted more free help on his computer, I told him my rates were comparable to his. He never asked me for help again. It turns out he treated others the same as soon found he had no free help for what he needed. He thought he should charge for his help, but get free help from everyone else..