This is a very important part of building your web site and should be your main consideration. You need to know what you want to say on your website and how you need to project your image as a company. It is important to understand your target audience as this can have a big bearing on your content. Ensuring your website is content rich will help us to make sure your website is ranked highly on the search engines.
Where will content come from? - will you write this yourself or do you need us to help you?
Will it be new content, or previous content with a new purpose?
How often will you have new content?
Who will update the content?
How much content do you want to provide?
You need to be clear about who is responsible for creating (what) content, the volume of content on your site and how it is going to be maintained.