A common mistake is thinking of a website as the end, when in reality it's just one step on the way.
All websites should aim to bring the user 'through the door' of your business as quickly and efficiently as possible. Think of your website as the door. Get them to open it and step through with ease. Once they're through the door, they're now your client.
The goal of most users is not to spend all their time on a website. It’s to get off a website. The good designers know this—and they bake it into their products.