But my biggest advice, make sure you properly comp the property. 

My biggest advice is to start investing where you have a good network of people you know like and trust...this especially holds true if you will be investing out of state.While it's not impossible to go straight to the commerical I personally found it easier to start in the residential world and then make my way over to commerical multi-family. 

I currently haver a private mortgage on the property that I will need to refinance in about a year or I have to pay a baloon payment. 

That was the biggest benefit that came up time and again was the amount of time that they stay in the property reducing turnover.

This can be hard money lender, private lender or bank.  

@Sandeep K MamidiTo flip properties effectively, use market knowledge, research local trends, and innovative financing options like private money loans, partnerships, and syndicatation.

Private money lending.

Quote from @George Goldstein: You know how when you buy a used car from a private seller you tell the seller to say he sold it for $3000 instead of $18000 so your dmv tax is lower?

My STR is in a city where it is legal in private but not in public.

The biggest trade off I have heard from someone (also not a CPA/tax advisor) that qualifies as REPS is upon sale, you no longer have long term capital gains, but rather active income.