Before beginning the design process, it is important to have a clear understanding of what your website needs to accomplish. This includes identifying your target audience, the main purpose of the website (e.g. selling products, providing information, etc.), and any specific functionality that needs to be included.
To help determine this information, you may want to review other websites, especially those of your competitors. Decide what you like in other websites, and also what you dislike. Think about what features and functionality might be wanted by your targeted customers and what items might give them reason to spend more time on your website and increase conversion.