First duplex - Too good to be true?

[Melanie Carter]

Just bought my first investment property  and am eager to move onto the next.  Before I do, I'm seeking some retroactive advice on the first deal to see what I might have missed or left out of my analysis: Bought duplex for $84K.  100+ years old property, but in great condition (per inspector) with newer roof, siding and windows and a dry basement (property was owner occupied for most of the last 15 years).  Monthly rent is $1,000 ($450 for upper, $550 for lower).  Property taxes are $1,888/yr and insurance (commercial policy) is $818 / yr.  Commercial loan at 5.25% with 20-year amortization.  I put 20% down.  Inclusive of pre-paids (including initial year's worth of hazard insurance) and closing costs, I'm in for $19K.  I did not include a vacancy factor in my calcs since I think both tenants will stay and, if they don't, I shouldn't have trouble finding new tenants (property fills a medium quality niche that is somewhat lacking in our area).  I pay $50/month in utilities (sewer/trash); All other utilities and lawn/snow is handled by tenants.  Included 20% capex allocation in my calcs (which might be low.  The garage needs a new roof and while I expect the tenants to stay, once they leave, I'll do some cosmetic sprucing up) and am planning to do the property management myself.  My calcs show me as having a cash-on-cash ratio of 4%.  Thoughts?