I bet there are some ways you could proactively plan so the problem almost resolves itself. 

The investor sector of the real estate agency side is different than the residential (more single family heavy) side for many reasons.

Here is the story:We sold a portfolio of rentals to a single buyer and part of the deal is we held back a 10% mortgage. 

A solid single will build your confidence and teach you a ton.Know Your Exit Plan: Have a backup—rental, flip, or sell later.

Sub-$350K single-family homes rarely cash flow in Charlotte, so consider properties with value-add potential or slightly outside the city.

One of the lease for a rental is about to expire and would like to change from single family to rent by the room and try, to market for regular leasing we normally go to Zillow and advertise for free, but for rent by the room not sure which of all the sites out there will be the best option(s), some of them are for free, majority pay a monthly or anual subscription ($99 to $200).Do you have any guidance on which to select?

It might not cashflow well as a rental/because it's a single family but if you can make it break even for the time being with a tenant, not a bad option as well.

Also, cost segregations are usually done on multi-million dollar assets not single-family homes.

My clients are still buying long term stabilized single tenant NNN more 10 to 15 year type stuff.I am buying with my syndication all cash short term lease blend and extend opportunities.Accredited investor 200k minimum per property for LP'sTypically pay 8 pref on value add deals and split cash flow thereafter 50/50 between LP and GP.Closed on Walgreens last month at 11 cap rate absolute NNN with 5 years primary term remaining. 

What do you feel your greatest need is as you transition from single-family to multifamily?