The most excellent John Walker has written a wee bit of advice for aspiring games journalists, and I reckon much of it is relevant to all kinds of freelancing.
Â This job is a not a privilege. Itâ€™s something you got by being good at what you do â€“ you earned it. Anyone who tells you itâ€™s a privilege is trying to get something from you they shouldnâ€™t have. Thatâ€™s the language of those who want you to do just a little bit more work than theyâ€™re paying you for, or put up with conditions that donâ€™t feel appropriate.
…Make a fuss. Good grief, the number of times Iâ€™ve not been paid for work, or screwed over in some way, is awful. Itâ€™s generally down to incompetence rather than malice, but itâ€™s unacceptable.