The marketing funnel is a critical part of any business but what's more important is understanding what part of it you need to be focussed on fixing.
While there are many many variations of marketing funnel in it's simplest and most practical form there is a few primary areas:
Awareness - do people know about you
Consideration - they are considering purchasing amongst other options
Intention - they intend on purchasing with you soon - perhaps there are a few other options left
Purchase - pretty self explanatory
Repurchase - again pretty self - explanatory
All too often it seems that people worry far more about their awareness problem rather than tackling all the other, frankly more valuable parts of the marketing funnel.