@Michael Yi adding an additional bathroom and/or adding an additional bedroom can provide excellent returns.

I've tried QB, Quicken Rental Manager, Buildium, Rentec Direct, Appfolio, RentPost and good old Excel.  

At the same time, I have a rental property and use my home computer to communicate with PM, update Excel spreadsheet, pay rental expenses, etc.

When the shows had only one guest they were excellent and offered invaluable information, however they would have been better suited with David Green.

To maximize the number of transactions you’re involved in you will need to:Be Top of Mind when they think about moving - which requires consistent reminders.Be seen as an Expert – which requires a consistent message and Evidence of Success storiesGain their Trust – which requires communicating integritySo, start out by listing everyone you know in an Excel spreadsheet.

Biggerpockets.com definitely have pro forma excel spreadsheets that can help. 

@Mike Gennaro   Rachel H. has a book called "Adventures in Mobile Homes" plus an excellent blog called Adventures in Mobile Homes. 

Other types of systems-built homes include panelized wall systems, log homes, structural insulated panels, and insulating concrete forms.

Lots of factors to consider... insulation, window R value, etc. 

Can also do it pretty easily in excel.