How to split income when one investor plans to live in one unit

[Vin Lanzafame]

Considering my first rental property. My sister would like to buy a two-unit rental property, finance it as her primary residence, live in one of the units, and rent the other out. She’s asked me if I want to split the costs and income with her. This seems like a relatively low cost way to enter into the investment property world. The question is how to split the income. If we split closing costs, do we then just split the income from the second unit and she pays for the mortgage, or do we have her pay market “rent” to ourselves, pay the mortgage, taxes, and insurance and then split the remaining profit each month? Or maybe there is about better way to handle this situation. Undecided on whether to put both our names on the mortgage or just hers. Hopefully someone can help! Thanks