I think Brand Loyalty starts with a good looking site, that is easy to navigate, and the customer gets what they want when they arrive at your site for the very first time.
In that first visit you want the customer to be exposed to other things on your website which will also be of interest to them, “hey this is cool too!”
From there, the odds of them wanting to come back to a site which has been of use to them increases.
Maintain a community, and updating a base through email, support chat, and forums all definitely work! – Cant forget the big one, social media too!