To support my seller and seize a valuable opportunity, my business partner and I decided to purchase the property ourselves.

Hard money beginning a great tool simply depends on the property you are flipping and the lender you use.

BP has various tools to help you analyze your deals (rentals, flips, wholesale, etc). : https://www.biggerpockets.com/investment-calculators7.

I'm wondering what tools and resources you all use as rental owners and investors to get or keep your financial ducks in a row?

Hello Preston,Thanks for the advice and valuable website.

Buyers and sellers should consider some amount of closing money be held in escrow after closing to cover potential problems with the non-responding tenants.Does anybody have any experiences to share with successful use of a Tenant Estoppel Letter, or times they wish they'd know about this tool before entering a Purchase and Sale Agreement?

You could use tools like Airdna and Pricelabs, filter for 30 min listings, and see what it tells you.

Don't use it strictly as a tool to turn the property into one you want to live in. 

Your old carpet did not become more valuable over the seven years you owned the property, even if you are selling for a gain.

I use the fix and flip tab and it's great it tells me my allowable offer and all the tools are helpful!