Some good ideas here that will probably save legal fees from Lansing State Journal's 8 tips to consider when living together
1. Get a cohabitation agreement. Do your research. If you can afford it, go to a lawyer. If you can't, there are a number of good books on the subject, and standard forms you can download for free online. You can then amend them to suit your particular circumstances.
2. Decide what your cohabitation agreement will cover. Make sure it covers the three biggies:
Assets. Are you sharing, or are they separate? What happens when one party contributes money or labor to an asset?
Support. Does either party have an obligation to support the other? After the relationship ends?
Is either party obligated to pay the other for services?
7. If you have a high net worth. Attorneys say you have an extra incentive to maintain good boundaries and get it all in writing. At the very least - keep all your finances separate, and make it clear that cohabitating is not a promise of lifetime support. And, you should definitely see a lawyer.
8. If you've been promised financial support. It doesn't mean a thing if you don't have it on paper. Get it in writing. And don't move in until you do.