Never underestimate a vendor's willingness to say yes to a project that it knows it won't be able to carry out. I'm entitled to give this advice because I did exactly that.
Rule 1: Don't base your vendor choice on personal relationships.
Rule 2: Don't assume that a vendor with general skills can handle specialized projects.
Rule 3: A vendor's references to specialized solutions need to be subjected to high degrees of due diligence.
Rule 4: The formal specification should always be complete before work commences.
Rule 5: Payment should reward not just time but also the complexity of the task.
Rule 6: Insist that vendors be responsible for all aspects of system integration.
Read this HBR blog post
