Now with time and rent growth, what could be a negative cash flow property might very well become a cash flow king, but that takes patience.Another way to increase cash flow would be renting out rooms in the unit you live in, either Airbnb or longer term.

The downside is added work, increased taxes probably. 

(Supply is also going up, but not fast enough to stop the rate of rental increase.)

Numbers appear high level comparable to the ones above, though both purchase price and renovation need to be financed on hard money, significantly increasing the carry costs.

He would get his first property for his portfolio, and I increase my cash flow by knocking out my biggest expense (rent).

Does clearing away years of overgrowth that has actually starts to affect the integrity of the structure and allows the house to be seen an actually entered increase the value measurably?

unless the neighborhood is gentrifying, C Class is probably not going to increase in value very much.What about the condition?

It might sound like a subtle difference, but keep in mind that the property has to appraise for that increased amount that the seller is crediting back to you. 

One offer with conventional financing and another higher offer with seller financing.This way he looks at the higher dollar figure and is more appealed to that offer.As suggested - it also helps to provide pros/cons for the seller to do seller financing.He might find it attractive if he is nearing retirement and still looking for an attractive rate of return via the interest rate on the seller financed note.

They could decide that they no longer want to allow owners to rent out their property or drastically increase the fees that could eat into your cash flow.