IANAL, but here's what I did for SeqCentral.
1) Look around the web for the Terms and Policies from similar companies. (Since SeqCentral is SaaS provider, I looked at GitHub, 37 Signals, and our competitors.)
2) Look at the Wikipedia pages for more "official" references: http://en.wikipedia.org/wiki/Privacy_policy and http://en.wikipedia.org/wiki/Terms_of_service
3) Draft your own terms such that if you were a user, that you would be comfortable with them. (I'm an idealist, and as such, the SeqCentral ToS centers around the right of the consumer rather than the tyranny of the provider.)
4) Iterate with a lawyer who will tell you what you need at a minimum. (e.g. Refunds, children (COPPA), health (HIPAA), EU or CA rules, etc.)
5) Sleep on it.
6) Post as a "draft", issue an RFC, and be ready to make changes as needed.
Best of luck.