Generally you want to maximize your returning users, and you do that by making their experience as smooth and pleasant as possible. Here are a couple of tips to help you maximize retention.
Assume users are idiots. The simplest way to build around the inevitable headaches they’ll run into is to make everything as easy and straightforward as possible. Stick to a clean UI that prevents them from getting lost.
Repetition makes the dream work. Repeat common patterns so they get ingrained, making the experience more intuitive — the less users have to think about what they’re doing, the more time they’ll spend on your content. Think about how you’d want to traverse a large website: it’s nice to know it’s organized in a standard way, whether via a hamburger menu or an always-present side panel. However you choose to organize, stick with your patterns.