Many startup founders dabble in freelancing or running a services business, as a way to wean themselves off the corporate feeding tubes, before starting their first company. If you're thinking of doing that, or you're in the middle of it, reading this article will save you potentially large amounts of money and hassle.
It proposes a number of clauses that should be in any software creation contract - such as keeping the copyright to your work until paid, defining where lawsuits will be settled, or declaring who is responsible for testing the product and declaring it finished.
If you're based in the US, this article is directly useful to you. If you're in another country, you may have to find a similar article in another country (if you know of one, tweet it to me and I will add it here).
In my experience, spending £10-100 or equivalent on a standard contract template can be well worth the cost precisely because decent contract templates will include all those clauses.