Probably oil.I was reading an article about this the other day.

You'll get forums, blogs, and articles on how to do way too many things.

They are both great at learning the fundamentals.Also - here's a couple articles you might enjoy:How to Be a Landlord: Ten Tips for SuccessHow to Start Investing In Real Estate at a Young AgeOh - and don't forget to set up your Keyword Alerts!

Anyway the link to the article from @Brandon Turner is here:http://www.biggerpockets.com/renewsblog/2013/04/09/how-to-buy-a-small-multifamily-property/Take care and Happy HuntingPaul

He has a website at dornish.net and has numerous articles available that he has written, including one on legal entities.

As for tenant retention, I found this article useful because it sets the tone and signals the beginning of a positive landlord-tenant relationship.

It's great for getting into local conversations.Lastly - here's a couple articles you might enjoy:The 21 Best Real Estate Investing Books Ever How to Rent Your House: The Definitive Step by Step GuideSee you around the site!

Here's a good article from TurboTax: https://turbotax.intuit.com/tax-tools/tax-tips/Home-Ownership/How-Short-Sales-and-Foreclosures-Affect-Your-Taxes/INF19990.html Might also want to get some input from @Steven Hamilton II

That is more the situation that the author of the article I'm talking about seemed to indicate isn't uncommon.

Brandon Turner wrote a great article on the BP blog on apps a few months ago.http://www.biggerpockets.com/renewsblog/2013/07/26/real-estate-apps/It pretty much covered most of the ones I use including, Trulia, Zillow, Realtor, Google Drive.One that isn't covered is Evernote, it's great for keeping notes and docs in the cloud for quick access anywhere.