I like contracts — they tend to simplify writing gigs because everyone knows expectations, payments and other details of the project. My rule is always get a contract.
I break that rule regularly, though.
I routinely write fairly short pieces — one offs for clients — that I don’t draw up a contract for. I also do short pieces for publication that I’m comfortable skipping the contract. It comes down to the simple decision of how mcuh the project is worth. If I’m writing something that I’ll only get paid $35 for, perhaps just a half-hour of work, it’s really not worth my time to get a contract.
On $35, after all, if a client decides not to pay you, there is surprising little you can do to collect, even if you have a contract. It costs far more than $35 to take someone to small claims court, even if they live in your immediate vicinity. It sucks, but that’s life.
Even if I can’t protect myself with a contract, though, I do take measures to guarantee that I’ll get paid for my work. Just Googling a prospective client’s name can be enough to show if he’s caused problems for any other freelancers.
Working without a contract is acceptable, at least in situations where it would take more time to draw up a contract than it would to complete the project. I do recommend them, though, for any project involving a significant sum of money.