Consult a lawyer, of course. You could pull in the T&Cs from firms that seem similar to yours, analyze them, learn a bit about contract law, and aggregate them to match your preferences, but the cost of the time you'll have to spend is quite likely to exceed the cost of getting a lawyer to modify some boilerplate to your particular needs.

You could also consider looking for a legal team member or mentor that could either contribute directly or steer you towards an attorney experienced in this space. As I've said for a while, having a plan for your legal needs is just as important as having one for server infrastructure etc. There are more legal grads than there are legal jobs at present so this might a good time to seek a business-minded cofounder with legal training.

If you're not sure where to start, call the bar association in your state and ask for a referral. You could also consult DIY legal texts such as the NOLO series, which are often quite well written and helpful, but knowing nothing about your business it's very hard to say how well or badly they'd fit your needs. Also, they're mainly aimed at consumers so I don't know if they'll cut it for B2B stuff.

The Small Business Administration has general resources: http://www.sba.gov/category/navigation-structure/starting-ma... or this affordable book provides an excellent introduction to the general principles of business law and the sort of situations any business owner should be prepared to encounter (the whole series is good in fact): http://www.amazon.com/Business-Law-Barrons-Review-Series/dp/...