When working with clients, one thing we notice is that many are focused on site design.  Equally if not more important to consider prior to starting any new site is function and usability.  A nice site design is great, but understanding how your customers interact on your site must be understood first.
 
Typically, the purpose of any website is to prompt a sale (product/service/information).  Understanding how customers navigate through that process is essential.  
 
Here are three essential rules that will help you to think through the process:

1. Make it Easy.  Confusing navigation is a deal killer. Make it easy for customers to find the products or services they are looking for.  Think about the multiple ways someone will look for something.   Create an outline and test it.  Make sure it’s easy to navigate to everything on your site.  In thinking about your navigation headings,  don't say (for example) "pumps" when you really mean "shoes".  Think through the hierarchy of the selection.  
2. Make it Obvious.  Don’t hide the customer service essentials, such as links to shopping carts, phone numbers or other relevant contact information.  The easier it is to find, the more it will be used.  Put timely information up front.   
3. Make it Relevant.  It’s a drag to go back to a site that’s not updated on a regular basis.  Ask yourself what makes you keep coming back to a site over and over?  Relevant and timely information.  That takes work and time.  If you don’t have it, find someone to help, it’s that important.  Check for broken links and invalid pages.  Simply adding a blog feed will help to provide consistent, timely info to your home page.  Update home page articles regularly, especially if you're retail.

Finally, once you have your site set up and running, give it some time and then go back and study how users are interacting.  Are they getting stuck and leaving pages?  How are they navigating to your products or services?  Can you make this quicker for them?  Is the information on that page relevant to what they are searching for (does the page have a high bounce rate)?  If not, it's time to revise the copy on the page and then measure again.  Yep, it's the old "wash, rinse, repeat" cycle again.

This time, you'll be able to see your improvement, because you know what you're measuring.

Keeping these three guidelines in mind when creating and managing your site will save you time and also help to gain sales.