If you take the cash out through a refinance you avoid having to refinance again in 3-5 years.I see a lot of investors get stuck with high DTI issues when trying to use a Heloc to buy another property versus a cash out refinance. 

Any issues to look out for or avoid?

These allow you to bundle renovation costs, and if the post-renovation value meets 20% equity, you may be able to avoid PMI.

By making partial dispositions, you can also avoid subsequent recapture on these items when you go to sell.

I generally avoid wholesalers because my experience has been that they are unwilling to use a standard purchase agreement that is fair to both the buyer and seller and they do 'shady' stuff.

Remember, a bad investment can cost you way more than the tax bill you're trying to avoid.

Fortunately, you will be able to to a 1033 exchange into new property and avoid any tax on the gain. 

They skip that property and send someone to verify and come back to it later after they know if they were paid or not to avoid a situation like may have happened in your case.

For the most part its just health and safety items, which are items we should have remedied anyways.As someone else mentioned, biggest thing to avoid is having the house tagged as vacant which the city will do if it sits empty for too long (handful of months, grass not cut, etc).

Remember, no system is perfect, so avoid the temptation of constantly chasing after the next shiny object.