For instance, in CA, contingencies are customarily Active, meaning a Buyer needs to actively remove them in writing.

For instance the price you would buy a house for and the price you can rent it for evens out often which creates little or no cash flow.

Also, have you learned any valuable lessons in instances where you purchased w/ cash (I am including private money, hard money, and HELOC funds when I say cash)?  

Any mathematical data if for instance I send out 1K letters?

If you can get to know an area, and its trends, you can get to know where, for instance, rents are pressing higher, or where new employers are coming in, or new development that benefit a neighborhood (like a Microbrewery).  

For instance, do I focus on the sqft, year built, taxes, etc?

In those instances, it is all the more important to have EVERYTHING in writing.  

Flipping lots in Lago was how I got started in Real Estate in 1989,  I used to send letters for people to give me their lots and in some instances I would pay $100 or so. 

For instance, the property values in my neighborhood have been exploding the last few years.

Only a licensed attorney has all the laws, regulations, and rules relevant to the disposition of the unique facts of your particular case.For the vast majority of instances, most new investors can be relatively safe with an LLC.