Often the tenants' checks are not received before the mortgages are due, meaning that their needs to be extra money in the bank account to pay mortgages before the rent checks are received.
Don't put yourself in a position of losing a substantial amount of your profit through prepayment penalties if you want to refinance in a year or two or if you sell the property.
An assesment of "hard and soft" value adding should be calculated before you buy and not after the deal is done.
Real estate brokers provide every kind of help to sellers as well as buyers.