You won't be able to think of everything to save yourself from critical mistakes.

As indicated we ran into multiple unexpected issues but also it was our first time rehabbing a unit that was old enough to have lathe and plaster (whether built in 1901 or 1920s).Did we make a mistake re-doing the entire plumbing and electrical rather than just what was necessary?  

One of the biggest mistakes I encountered in years doing remodels and builds was when a customer wanted to do their own painting to 'save a few bucks'.It was a disaster - every. single. time.A pro painter is a huge plus to the finish fit and feel of any project, they are just too good.

Every GP, real estate investor, makes mistakes, doesn't time the market perfectly etc, looking for the perfect is the enemy of the good. good REITs right now, take a look at ADC - agree realty, does multi-tenant triple net large shopping centers and has better growth outlook than Realty income-O-, 6% vrs 4%, which is also great company, both stand to benefit from low supply of retail space, last 5-10 yrs construction-wise, and thus better rents going forward, and interest rates should fall near term, lowering Cap rates and increasing underlying asset values and sales proceeds (only hold REITS in a tax-sheltered account, 401k or IRA, due to high taxation of the dividends-ordinary income) Good Luck

The biggest mistaker I mad when I started buying deals, we were self managing.

If you supply the materials , and you order the wrong stuff , or dont order enough , and the contractor is there with 5 guys and cant work due to your mistake .

Seems weird it would make such a basic math mistake. 

They deal with 100’s and the IRS deal with hundreds of thousands, they’ll spot a mistake at first glance.

Basically own your mistakes or short comings.I have only ever given 1 full refund and it was really just to get scumbags out of my property early.

You'll need to make decisions, and do a lot of research to minimize mistakes for out of state investing.