Seller financing, how to know if it is a good deal?

[Colton Kotylo]

I am trying to purchase a triplex using seller financing. This will be my first home purchase and I am unsure what terms I should propose and how to calculate the deal to see if the numbers will work for this property. The property is currently being rented out with two of the three in a long term contract and the third paying month to month. Who would be the best person to talk to in this situation?