Due Diligence.

[Kay Rock]

Hi BPs.

My Duplex is finally coming through, I got the appraisal back, which was more than the the price they accepted.  So far, I know I have to replace /update the roof, electrical panels and some windows among other things. The duplex is rented, however, it is way below market value, so I asked that  the tenants to leave prior to closing. I have a studio rented on my house, but now i want to treat this more professionally. 

What are some due diligence I need to be doing, prior to closing and vetting for tenants? This is a duplex 3/2 and 2/2. 1 water meter, separate electrical meters.