Its pretty simple.  In today's digital world, if you are not paying for ads, you have a hobby, not a business.  Before you start to pay for advertising however, you need to know the mind of your customer.  Where they live, what they care about and where they go.  Its no different that trying to decide where to put your road sign in the real world.  Where your prospects eyeballs will be.  That's the trick!  Few will be successful, especially smaller businesses, without paid traffic at least being part of their initial marketing budget.  Once you figure out the path to purchase, then you can refine and take the costs out, leverage social (if that works!), etc.  Understand your customer (persona!), theorize an effective message, plan your campaign/develop materials (brand, message, collateral, venue), implement, test/test/test, adjust, rinse, repeat.