Take time to read Michael Masterson’s Ready Fire Aim.
A lot of entrepreneurs spend a lot of their time on office space, beautiful web site design and other secondary & tertiary tasks. If no one is going to buy what you want to sell, you’ve just wasted a bunch of money on a business that will never be.
This book reemphasizes the need for sales as the most important activity for a startup. I believe a startup will be out of business if they cannot generate sustainable sales within 12-18 months of starting.