Any advice on what I should do (or not do) and things to consider starting off would be greatly appreciated.
I can't help you with the ATM thingy since I haven't even seen one personally nor tried it. And I also have no plan of it as a business but you should also consider the popularity of bitcoin in your place. Whether there are a lot of users that might use your ATM or not. Start your planning before purchasing one. It's always better to start with a plan. Estimate if you'll be able to gain profit from it, how big is the possible profit, and the time.
As I mentioned above, any profits I make from the ATM will be going directly to the IRS for the foreseeable future because my wife and I are trying to pay down a not-insubstantial amount that we owe in taxes. Maybe I'm crazy for thinking this will be an easy business venture by which to pay our personal tax debt, but we're willing to try it. If we have crazy success beyond paying our tax debt by this means, that's just icing on the cake.