Many publishers work from behind their desktop PC’s and laptops, and therefore mainly focus on how the website looks on those screen sizes. They kind of look at Mobile as an extra thing to do.
BIG MISTAKE! Mobile is more important than ever. In fact some have declared Desktop SEO to be death. This is because in 2016 google announced that will be indexing websites with ‘Mobile-First’. Entrepeneur has covered it nicely, but essentially it means that google will now visit your website as if they are a mobile visitor. When the google bot can’t find links because your site structure is off on mobile, or because your website is very slow, it will consider it to not be a mobile friendly website.
Things like site structure and speed are very important, and should just be done like you have done for desktop. Make sure it has a menu etc etc (see image above).
An other easy thing to make sure of now is that your website is responsive. Some older websites still aren’t, but if you are running a WordPress site, chances are likely that your theme is already mobile responsive.
Check it with Google’s Mobile Friendly Tool .
If it is not responsive, change this ASAP! Make sure you get results like this: