I do a lot of "one-off" jobs as you call it and I usually don't do a contract, but it all just depends on how I feel about the client. If I get an iffy vibe from them then I'll ask for a contract and up-front payment, but in my biz I get a lot of single project jobs especially around tax season and I don't bother with a contract, but I also get paid immediately at time of service.

I do contracts for ongoing jobs that I will be billing out, just so everybody's on the same page as far as terms, pricing, etc. Luckily I've had great clients so far and it's never been an issue, but I learned working in the corporate world that you have to protect yourself. If you don't have a contract and someone decides not to pay you don't have many options legally.

__________________
Rebecka Melson ~ Virtual Business Services