Firstly, consider how your visitors will be thinking when they arrive at your website.  They may be thinking "Can I trust them?" "Are they any good?"  "Will they get the job done?" or "How do I contact them?".  Make sure their questions are answered easily when they arrive at your website.

With a multi-page website, you will not necessarily know where your prospective customer will be when they decide to contact you.  Therefore, try to ensure the "Contact" button is visible very easily - it should be visible in no more than one click.

New customers are not the only consideration, although of course they are important!  Your existing customers already have first hand knowledge of how you work - but your website can be used to promote goods or services that they may not currently know about.  One of the best ways to give your customers what they want is to ask them!  A simple, short questionnaire asking customers what they would like to see on your website will help to point you in the right direction.  This process is called "usability" and it helps your website work for you.