My favorite phrase:
Schulz Consulting is NOT in the business of providing tax, payroll, accounting or audit advice. You are advised to consult with your tax or accounting professional on all matters related to proper tax/accounting rules and regulations. No advice we provide should be interpreted as tax, payroll, accounting or audit advice.
Schulz Consulting's sole liability with respect to this support agreement and the services provided as part of it shall be limited to a pro-rata refund of the unused portion. You agree that Schulz Consulting will not be held responsible for consequential damages in excess of the amount paid under this plan. Data backup, accounting record review/reconciliation and PCI and payment compliance is your company's sole responsibility. This support plan does not provide for testing or maintenance of a backup procedure which is your sole responsibility.
I pulled these form our support agreement but I think they're the most important concepts and you can modify them and/or expand.
https://docs.google.com/a/s-consult.com/document/d/1U8kubJ1HIrVUTl-RjJ8OTAosdwKmuusUxoy5POwe79w/edit?hl=en_US