He does good work and is easy to work with.

Most investors want something easy.

Under $150, easy to install and use, tenant can set their own code but landlord can retain the master and always have access, tenant can't lock themselves out, standard key for emergency backup, batteries last a couple years, etc.

As for a downward shift you can always lower your rate (underwrite a worst, middle and best case scenario), Make sure your rental stands out from the crowd (easy to do in Hawaii since most owners don't reinvest in their property).  

Then, with reasonable confidence you can estimate costs.I personally don't love the square foot estimating method for remodeling as I think it is an easy way to lose.

Communication is table stakes and is easy to assess.

Neighborhood Drive-byDoing a neighborhood drive-by to look for foreclosures may seem like a dated approach, considering how easy it is to search online.

If you have never done this as a full time business I will throw caution to the wind it is not as easy or as profitable as online forums make it out to be, and if you need money for living this probably is not going to sustain your lifestyle for the first several years. 

Pre-internet, being a landlord wasn't easy, but it was straightforward (this is a gross oversimplification).

Exit Strategy: How easy/difficult has it been to sell units in similar properties?