95% of the problems that landlords have is due to poor (or no) tenant screening processes. The landlords who do good, thorough tenant screening are not the burnt out, bitter ones. They are the ones who are always smiling. Here is a link to a fantastic Bigger Pockets blog post called "The Ultimate Guide to Screening Tenants": http://www.biggerpockets.com/renewsblog/2013/01/27/tenant-screening/. After you get done reading that post, you may wish to join Bigger Pockets here: http://www.biggerpockets.com/. It's really a wonderful resource.
Matt Taylor, firstname.lastname@example.org, New Hampshire Private Lending