I am in the Miami area and just wanted to know any tips that I should take as I start this journey.

I am primarily looking at properties in Miami in the $315k range, preferably homes. 

Plan on paying for new heating and air conditioning units (HVAC), hot water heaters, roof repairs and replacement, and plumbing issues to say the least.

You can save money by doing  some things yourself but you always open the walls and find something like electric or heat that isn't a DIY. 

Look it over, especially for things like type of electrical wiring, heat-does is include all rooms, and old termite and dry rot damage. 

Electrical, plumbing, and heating are not split between upstairs and downstairs, though downstairs has in-wall cadet heaters.

Would you say would be the three must do renovations that help reduce my electricity and heating bill building wide?

Ft.Lot size = 15,002.06I'll need to add heating and cooling; currently window units.P&B construction for the houses and duplex, slab for the studio.Total projected gross rents= $750 Studio+$950 Unit 1+$950 Unit 2.The whole project would be a value add: windows, bathroom, update kitchen, furniture, solar panels, water purifier.I'm considering adding solar panels - would mean that I can charge for my own electricity sense I would be the power company.Property Management fees = 7% (wholesaler/broker number).Projected Vacancy Rate = 5% (wholesaler/broker number).CapEx = 5% (wholesaler/broker number).The military gets their BAH/BAS evaluated every year and it goes up about 2.5% based on the market conditions.Property growth annually would fit in to a 3% number as its not the fastest appreciation market.Your annual expenses should be about 1.5%-2% depends on how well of a job is done with the rehab.P.S.

Flader Plumbing & Heating (located in Evanston) did some emergency plumbing work on my 3-flat last summer and I was happy with them. 

A few things to keep in mind:Your taxes will likely got up due to the renovation/new sale.Confirm if this is on 1 heating system for separate utilities.