The web is built largely on the principle of serving desktop users. The real web, the real advancements in technologies, is best displayed on a beautiful full-screen display. But, smartphones and other mobile devices are a thing, and it’s time to start adapting to the concept of mobile-first design.

Other than the common-sense responsive design, what other design elements you ought to implement in your mobile-first web designs?

Prioritization. Mobile screens are limited to the available display space. Also, mobile screens present content in a vertical manner opposed to much wider — horizontal — structure for desktops. This means that you must design using prioritization. Which elements are of utmost importance for users to see? If there are CTA buttons, how easy it is to see them for the mobile user?
Content first. Color second. You can do some interesting things with mobile design, but certainly not in the scope of desktop design. So, give way to content first. Make your copy and other content parts easily readable and accessible. A mobile screen is much less forgiving on distracting visual elements.
Easy navigation. On a mobile device, you can’t just click anywhere and return to the homepage. Unless, of course, you plan for this type of navigation ahead of time. And you should. Experiment with Scroll-to-Top widgets, but also seamless sticky headers whenever possible.
The best way to check whether you’re doing this right is to use your phone (I do it all the time!) and visit your site. Do a thorough examination of how things feel and flow together.

If you’re sitting in a cafe or waiting on a flight in an airport, poke someone on a shoulder and politely ask them to check your site for you. Then, sit back and hear their feedback. Most times you’ll surprise yourself with the way people perceive the user experience of your website.