This was an invaluable experience and a key ingredient to fast tracking our success.

Earning a nice salary will also help you kick start your business.There are no one-size-fits-all ingredients for success, but in my opinion the path of a higher probability of being successful is going to college first.

@Larisa Dalekorey - I see a lot of opinions on this thread which can be great but I think you left out a key ingredient to the equation.

Taking action is the key ingredient.

I also agree that not being a slumlord and having good PM are key ingredients in not being sued regardless of the way you go with it.  

That is a critical - and often difficult to achieve - ingredient in your plan, and one that has only become more challenging with changes in the labor markets the last couple of years.

The most important ingredient in real estate investing is TIME!

Fresh ingredients aren't cheap, neither are lessons, gear and memberships, but I spend my money on them because doing these things bring me joy. 

This is no different than a baker using $1 of ingredients to make and sell a $4 chocolate chip cookie.You can only flip so many houses, so the ability to scale is based on your time and energy.

Lots of ingredients in this soup.