Still, Zapinski says she "might make an exception" if a vendor has been in delivering patches, upgrades and other fixes over time.

7. BYOC.

Auer strongly recommends that clients bring their own contracts whenever possible and that they let the vendor know they will be doing so in the request-for-proposals stage of the deal.

"Here's a legitimate problem for vendors: If you pull out your own contract at the end of a deal, there's rarely a way for vendors to agree to it quickly," says Auer. That's because the lawyers representing vendors are familiar with their clients' formulaic contracts but would require additional time to go line by line through a customer's contract. In fact, says Wang, if you do insist on using your own "paper," expect to add three to six months to the negotiation process, even if you state your intention upfront.

In Disbrow's experience, customers outside the public sector almost always have to use form contracts offered by SAP and Oracle. But some customers say they're comfortable using vendor-generated contracts; they merely insist on amending them.