I’m active duty Air Force.VA loans are based more on “residual income” rather than DTI.Message me if you have questions.

What is the basic approach to produce 'residual' revenue?  

Then use the cash from that to buy my residual income. 

Residual smoke crept through the shared attic space and down into my unit.

Follow the signs of water...usually a white residue/deposit, black stained or soft wood, or actual moisture.If you are in a multi-story building, with yet another bathroom or apartment above your neighbors, the leak could be coming from ANY upper floor.

Also, my contractors got paid for the work and I kept management of the building after the sale for the current landlord, so my property manager is getting some residual from the deal.

i'm not sure about your obligation to the tenant, but most tenting for termites use Vikane gas which leaves little to no residue or post-fumigation clean up.

I am excited to start 2019 making money so I can buy investment properties and create residual income. 

My RE Dream is to have $1million in residual income from my investments by the time I'm 40. 30 would be even better (Countdown 7 more years!).

This is the approach described quite well by @John Becker above.The other approach, and this is the one used by developers like myself, is residual value.