Plan the path a visitor will take using only the keyboard – this is so important it directly affects how you write code. When designing your site structure, think ahead: what's the priority order of your regions? Consider this example:
The image above shows 6 regions.
2. Main navigation menu of the site.
3. Article-specific navigation area. If the article is long and divided by headings, include internal links to those sections.
4. The article content itself.
5. Sidebar – typically holds additional information about the article, links to other site areas, or other contextual content based on the site's design.
6. Footer.
I'm deliberately starting at number 2, because I always reserve number 1 for a skip link to main content (region 4 in the image). This link is the first thing a keyboard user looks for. You can style it however you like and according to guidelines – it can be always visible or appear when it receives keyboard focus.
The more complex and content-heavy your site, the harder it becomes to map the path a keyboard user will take. For example, a more complex site structure:
If you don't deliberately plan the focus path, the default order will be top-to-bottom, following the order in your code. If you've designed the tab sequence, communicate this information to your developer so they can structure the code correctly.
As your site grows more complex and feature-rich, mapping the keyboard user's path becomes increasingly challenging. The larger the site, the more essential planning becomes.
How to Guide Your Site Owner to Find the Right Keyboard Navigation Order
You know the question: "If you were stranded on a desert island and could bring only one thing, what would it be?" Apply the same principle here. Ask your site owner: "If you could publish only one thing on your site, what would it be?" (Usually it's a promotional article or something similar – when that's the answer, in my view it's equivalent to the main content area where the site's core content lives). After you get that answer, ask what's the second most important thing, then the third, and so on. This way, you can plan a tab order that makes sense for your site owner and works well for keyboard users.