I simply recommend writing a nice, sincere, non-threatening letter and getting it out to the homes in your market you feel would be a fit for wholesaling. 

@Roy N. certainly has a point around commercial properties and it's something most investors get to at some point (either the property is commercial or you have your residential properties, wrapped up as a commercial portfolio loan) as you simply can't keep qualifying personally.Another option is going with a lender which is able to qualify the self-employed.

You can do that but every dollar you take in cash or purchase less than what you sell is interpreted by the IRS as taking profit. 

For flipping sometimes it works in high price neighborhoods and the profits are much better with lower risk.

They view them as a taking of profit and it could jeopardize your exchange if audited.  

is the wholesaler is the one who brings the buyer, normally they add their profit on top of the price

I have flipped a property ($60,000 profit) and recently built my own home for $250,000 (appraised at $380,000).

Once you reach the number or properties/CF you want or simply when you no longer want to buy more properties, then that is the time to start paying down your mortgages.

If it is a new tenant likely hood is that the landlord simply placed someone with a heart beat without screening. 

Your market - do you end up more profitable if you charge back utilities with a lower rent, or you paying utilities and bump rent payments up.