Refuse free work
Many people will obviously tell you to refuse to work for free. I also suggest not to accept free work.
Most people guess a free work is fine to take, actually you should wrench the maximum of free work from as many people as you can get away with.
My point is beyond ethics (exploitation or fairness), but a basic advice for any business to be sustainable and mutually beneficial.
— — —
I’ve seen many friends accepting free work, as competitions’ prizes, favor to repay or such. What you get is you now depend on work that will probably be low priority or high resentment for your vendor.
I don’t like equating power to the power of nuisance, but it’s useful to ask that question now and then. If they are in an emergency, what are the consequences of a failure? On one hand, an actual customer with actual contract and payment to withhold or penalty fees. On the other, you and a gift not given. A favor not or badly repaid.
It’s hard enough to get people to do what you want, be they kids, spouses, coworkers, teams, bosses… given the emotional ties or constraints you have. Why do you think you will be able to exert command and control on people who are working for naught?
— — —
This is not to say you shouldn’t try to be flexible: I’ve seen and made many business arrangements for convenience or fair-play, which only exceptionally turn out not to work.
This is not to say you shouldn’t benefit of great opportunities that happen to look unbalanced. This is to say you should always check you vendors and deals.