I would advise in getting your website reviewed by 10-15 people(regular people/friends that could be a customer) with good questions about your website/product.
That will get you a step closer to how a client looks at your website.
Personally (as you did not offer any link to review)... I think most websites have a huge conversion problem because of their poor design, and the client's trust of the website/busienss/product QUALITY is lost because of that.
Of course Google Analytics have a huge role in fixing the pages that show up as having the highest drop off.
Hope it helps...
Just for my own curiosity what is the drop off rate for the home page of your website.