It's not what you can see, it's what you can't see that will reach out and bite you right in the behind.The only way you can even get close to a realistic cost study is to strip the home down to the bones, thoroughly inspect the foundation, check for adequate drainage away from the structure, thoroughly inspect the infrastructure including the cast iron and/or clay water and sewage plumbing and the electrical and gas lines. 

Was the previous landlord paying for something that we typically require the tenant to pay for, such as variable utilities (water, electric, natural gas/oil, etc.)

Make it a point in your property rules to have tenants maintain proper egress, clean the home regularly, use the ventilation devices appropriately, and report to you in a timely manner any mold or moisture problems.Here is a clause from our rental agreement that covers this....MAINTENANCE OF PREMISES.Landlord will maintain all electrical, plumbing, heating, and other facilities and appliances supplied by Landlord in good working order.Landlord will perform periodic inspections of the premises, no less than once a year, for the purpose of property maintenance and repair.Landlord will notify Tenant in advance of the inspection.

Especially if you aren't running plumbing or electric to it.

Purchase price 147KListed for 299K, sold for 285 (went under contract for 290 but dropped it another 5K at buyer request after the appraisal just to get out of the deal)Home Depot credit card: 10K (appliances, fixtures and other things we picked out and purchased ourselves rather than having GC use typical builder grade stuff, also husband did some of the work himself so bought his own materials)Brought 40K of our own cash to the closing table, loan total when paid back was 185 (original loan 175 plus 10K in accrued interest, 12 month balloon loan so we did not have to make payments during the rehab, which helped a lot with cash flow, also loan had rehab costs folded in so for the most part we paid our guys out of the loan and not our own pockets)So (numbers are round): 285 sale price - 185 (loan payback) - 40 (cash we brought to closing) - 10 (Home Depot card) - 10 (closing costs) = 40K profitWork done: insulation and vinyl siding (this ate 18K of rehab budget but was unavoidable as cedar shakes were disintegrating), converted to natural gas heat (ducts already in place, changed out electric hot air blower to gas one and gas company ran the gas from the street for free), replaced AC compressor, new water heater, two new bathrooms, replacement windows, new appliances but left the wood cabinets b/c they were in perfect condition and I could not justify painting/replacing them, new kitchen backsplash, removed wall between kitchen and dining room, wood laminate flooring throughout except for new carpet in downstairs den, painted the deck/railings, new garage doors, one new slider, all solid wood interior panel doors, of course fresh paint and new light fixtures throughout.dining roomThere was moisture damage downstairs from bank not winterizing and pipes bursting...thanks, bank.Hauled out enormous old woodstove and broke up ugly old hearth and left good flue for someone to add new pellet or woodstove to if they want to, we figured not everyone wants a woodstove and this way the buyer can decide to add one back if desiredBathroom off downstairs den, chose a walk in shower for variety, hosing off dog or muddy children, disabled access, etc. 

everything inside your unit you pay to upkeep,plumbing ,hvac,electrical etc.

A coin operated washer and dryer should pay for any increase in water or electricity and would most likely attract a better tenant class 

I made some structural changes to the house to provide clean water and electricity and raised the rent to market value.

I have a few TEsla's and I thought it would be cool to drive them around in my electric car when I am bored... but then I read I have to allow dogs and well that ended that. there are many ways to do real estate part time... and still service your clients. its not all residential you know.And real estate is simply not like it used to be.. if you have weekends and nights free you can make it work.I know when I sold real estate I played golf most every day during the week  130 to 140 rounds a year.. my clients were working I was golfing.. or flying my plane or what have you.. but come 4pm I worked every night till 10 and I worked EVERY weekend.. save thanksgiving and Christmas...

It tends to break down rubbers and some plastics including the coverings on electrical wiring.