Investment Property Financing Question

[Shion Queen]

Can you refresh my thought process on investment property financing?  If I finance a property as an investor (not a resident) on a duplex that is occupied with long term tenants and I put 20% down, would it be realistic for me to qualify if I have a high fico and the rents offset the mortgage?  I am concerned about the debt to income ratio. And what if the dwelling wasn't rented out yet, does that pose a financing challenge as well?