They say that their customers see a 30% increase in revenue but they don't make any guarantees.   

If it is, why can't you buy similar properties that you are renting with the money you make.If you get $200,000 annually(split proceeds with the other owner), you should be able to buy almost any type of property.

If you were to buy, let's say a three bedroom or four bedroom home and rent out the other rooms to other single people.If you were to get a short term rental, you would probably want to have somebody else manage it and right now your average short term rental isn't doing really well.

Do you build it with the intention of renting it or just for family/friend use?

I was working through the HELOC process since we have quite a lot of equity when I suddenly got denied because 1 of the 5 units is owned by someone who lives overseas and rents out his unit.

I figure we could rent it out to cover that expense, maybe make a few extra bucks on top each month and keep the house in the family that way.

that we’ve learned in our 24 years, managing almost 700 doors across the Metro Detroit area, including almost 100 S8 leases:Class A Properties:Cashflow vs Appreciation: Typically, 3-5 years for positive cashflow, but you get highest relative rent & value appreciation.Vacancy Est: Historically 10%, 5% the more recent norm.Tenant Pool: Majority will have FICO scores of 680+ (roughly 5% probability of default), zero evictions in last 7 years.Class B Properties:Cashflow vs Appreciation: Typically, decent amount of relative rent & value appreciation.Vacancy Est: Historically 10%, 5% should be applied only if proper research done to support.Tenant Pool: Majority will have FICO scores of 620-680 (around 10% probability of default), some blemishes, but should have no evictions in last 5 yearsClass C Properties:Cashflow vs Appreciation: Typically, high cashflow and at the lower end of relative rent & value appreciation.

Then I would like to begin investing and renting residential properties.

If you can make it look good in photos then you can list it for rent.

Then my current primary home will be rented out to balance the cash flow of this purchase for the next year or so.