As a freelancer, it is always good to get everything in writing up front. When dealing with clients, it is good to use your own boilerplate contract rather than theirs, at least initially. This allows you to make the terms clear and beneficial to your needs from the beginning, even if negotiation or transfer to their own contract is necessary afterwards. This is called a Letter of Agreement.
I have long used a variation of the sample that is provided through the Graphic Artists Guild. This is a printable version of their example.
In addition, they have a glossary of contract terms, as these are frequently used and can be misunderstood. The glossary can be found here.
I'm not a lawyer, but I'm always available if anyone wants to discuss usage rights, Work-for-Hire issues or anything along the lines of what we deal with when we put our business hat on.