I'm a "non resident alien" who has visited Ohio recently looking for opportunities.

The biggest problem is not identifying good investments  – just get the properties inspected & be aware America uses a Deeds system , so you should pay extra for title insurance. for the peace of mind., 

The biggest problem is  working around the suspicion of foreigners caused  by the post – 911 US Patriot Act.  A lot of realtors & banks & others are hesitant to deal with foreigners now because they are scared  being caught up in it if the FBI labels you a "terrorist" or "money launderer".  e.g. I finally managed to open an Ohio  cheque account  while I was  there,  but the bank says it has to send all my mail via Sweden ( a neutral country ) & it takes 3-4 weeks. That's good, though – 3 other banks turned me down flat to my face.

They won't actually say in so many words, because non-resident  property investment is usually quite legal ( just need to refer to the Realtors State-by-state Guide  http://www.realtor.org/NCommSrc.nsf/files/Alien%20Land%20Ownership%20Guide%20(November%202006).pdf/$FILE/Alien%20Land%20Ownership%20Guide%20(November%202006).pdf

So you have to be really committed to doing business.