This one might be more controversial in the community (heh, as if the other essays I've put up haven't pissed someone off). Personally, I don't believe it's right to charge people for casting a spell, doing a tarot/rune/I-Ching/palm/whatever reading for them. Charging for supplies is fine. If someone came up to me and asked me to perform some hugely complicated spell, and I had all the stuff, I wouldn't ask anything of them moneywise. But if they were asking me to do something I'd end up having to go to buy supplies for, I wouldn't hesitate to ask them to pitch in for their materials.

If you reeeally desire to pay someone for their services, and they don't want to take your money, leave it somewhere. Ask to use the bathroom and sneak it into their medicine cabinet or jewelry box, or something like that. If possible, stick it in their wallet. Don't argue with them or insist that they take your money. That's annoying, and if you keep bugging them, they'll be less interested in doing something for you next time.