With a great site and the right elements you can hope to draw readers in and keep them looking around, but the golden egg is your mailing list.
By giving you their email address, a writer is inviting you to contact them. With great power comes great responsibility and all that. While you see a mailing list as an opportunity to market your work, a reader sees it as a chance to get information ahead of the public and other benefits.
When it comes to contacting your mailing list, I recommend the 80/20 rule. 80% of your content should be reader focused, giving them sneak peaks, bonus content and early news. The other 20% can be reserved for marketing type information like book release dates, blog tour info and appearances. If your content is all "look what I'm hoping you buy" readers are going to tune you out. They may not actively unsubscribe, but they will stop paying attention which is just as bad.
It's never to early to start building your mailing list, even if you don't have a book out. You don't have to start sending emails right away. However, you should send something out every few months or so just to remind subscribers that you are there. This also keeps them from being surprised when you do send out that all important "I'm being published" notice.