Defining Investment Criteria

[Account Closed]

Just finished reading 'The Millionaire Real Estate Investor' by Jay Papasan.  One of the key points mentioned here and many other real estate books is to have a well defined criteria for your investments.

I tried setting a criteria in the past but it didn't work out.  I always question my own criteria and think if I should invest on north side where the market is stable but prices are high with less inventory or should i go West/south where there are a lot of low priced properties but many risks as well.

Should I look for single family homes or small multi family units since I can finance both of them with conventional loan ?

Or Should i just continue looking everywhere for properties for motivated sellers and just confirm that the numbers work fine. I have bought properties in the past without a definite criteria but this book makes sense and I would like to have a well defined criteria so that I can focus well. 

Therefore, I need help in understanding how can I determine my criteria when i don't have 4-5 years of experience in this market.

Does it make sense ?