I've made some previous posts about design systems, which are all the rage in 2017. We are still working through the creation of one at my organization. One of the core parts of design systems are principles.
These principles ideally shape the future of design for an organization. The most important thing that I keep coming back to when thinking about how to create interfaces is to be inclusive.
Be inclusive
This is the most important design principle you can have as an organization. Convincing people that it is important can take a lot of work and often times you will be fighting an existing culture that says "If it works on my computer then its good." A lot of people don't stop to consider all the other ways people can be accessing their site/content.
What does that mean?
If your creative team is well versed in inclusive design principles, then it's easy: Hand over design authority to your creative team. Are you reaching as many people as you can? If your superiors look at your creative team as tools that will do what they say and create what they want then it is incredibly difficult to design inclusively.
The problem with this approach is that often times the stakeholders who are "driving the bus" so to speak, are not well versed in performance, accessibility, and usability -- all three of these areas are vital to being inclusive.
Performance
It's nice that the site works on your high speed, wired internet connection, but how does it perform with spotty WiFi or on 3G speeds? Are you able to access the site in these situations?
Accessibility
I think this is what a lot of people think of when talking about being inclusive. Is your site designed and developed in a way that takes into account WCAG 2.0 (the de-facto standard for accessibility guidelines)? Complying with these guidelines helps everyone, not just those with disabilities. Microsoft has done a phenomenal job at explaining that disabilities are not personal health conditions, but rather mismatched human interactions.
Usability
Usability is closely related to performance and accessibility. If the site isn't performant and accessible then it isn't usable. On top of that, ensure your site is following agreed upon UI patterns to ensure a consistent experience across your site.
This is not a complete or exhaustive list by any means but it seems to me that keeping these three areas in mind will go a long way in ensuring that your site is inclusive.