Underestimating repair costs and overestimating ARV (this is really just what most people call wholesaling). 

Do you have people ready to repair and clean the place lined up as soon as the last tenant leaves?

Also, in a 1031 the seller cannot take possession of the funds so you giving him the downpayment to do repairs would be challenging.

The last tenants did some damage to the interior of the house and repairs like, sheet rock, fixtures, paint, etc. need to be completed. 

This is critical to include.Other technical itemsOnce that's done, be sure to include meta descriptions and titles, images that are 1,000 pixels or less, and alt text in your images that includes some of the keywords you're ranking for, when relevant.Build linksThen use HARO (now Connectively) to build natural links to your site by being quoted as an expert on flipping, home sales, home repairs, etc.These will be homepage links, but since you're going to be trying to rank your homepage, you're looking to boost your overall domain authority.

As long as there are no outstanding repairs, I don't see anything wrong with paying off that loan faster. 

Leaving you to move and store their items if required by law, clean and repair, etc etc.

At a bare bones minimum, the letter confirms the start/end dates of the lease, monthly rent, paid-through date, absence of any prepaid rent other than the current month, and security deposit amount.Better, it will include statements there are no unresolved claims or disputes or repair issues with the current landlord, and no verbal or written side agreements.Better yet, it will include a copy of the tenant's lease, and a confirmation the lease is a true and correct copy with no amendments.

If it's not you - you are going to be paying contractors (most likely) retail repair rates - and with the prices of housing (even dilapidated housing) pretty high right now - I would say that flipping is not the easiest "in" to the market.  

I'm thinking a house hack with a V.A. loan so you could slide with that 0% down and allocate funds for repairs.