During my investing career, I have found a great ability to manage all types of properties at a high level.

Turn key investments are at such a high negative cash flow that I don't think it'll be a viable option. 

They typically have multiple origination points (meaning very high closing costs) very high rates (compared to conventional but also compared to 6 month or longer waiting period DSCR products) and almost always have VERY long pre-payment periods up to 5 years.

If you are already paying high value, I'd renegotiate or walk.

I flip rentals as a primary and do it in pretty high volume & use any spare revenue not reinvested in this business to buy very high yield stable MFR in working class neighborhoods.

Many, if not most, want to have this data, but a very high % don't calculate monthly performance.

The rent is not super high. 

Because high rental yields, tax free income, and stable market. what do I have to learn first to start investing on Dubai's rental properties? 

Anything over that could mean that the property is overstaffed, or it could mean that management is delivering a very high level of service such as in a luxury property that has a doorman and all sorts of staff that you don't typically see in garden style apartments.

If he starts now he can buy his own car for high school.