The most common thing we do when we try to get as good a mobile experience as possible is that we build the web page on a good framework for this. There are several to Joomla and we have experience in most. We can really recommend UIkit from German YOOtheme (YOOTheme PRO is their latest addition to which we build most). By building on one of these (if you do it right) you get a fully responsive design that dynamically adapts to how wide the browser is. This means it adapts to how you keep your smartphone or tablet. Portrait or landscape gives different widths and directly adjusts the web page to take full advantage.
With a mobile-adapted webpage, you make sure it's neat and easy to navigate between the pages on a mobile phone. It is also important to customize contact forms and link phone numbers to facilitate even more for visitors using smartphones.
There are two ways to solve the ease of use in a smartphone; repsonsiv design or mobile design. In a responsive template, the content automatically adjusts to the width of the browser. For example, 3 columns - 1 column. At a so-called mobile-custom template, a completely independent stand-alone design is built for just smartphones (and older surfboards). The content is still retrieved directly from the database but another layout and menu is loaded when the webpage feels that it is a mobile device used by the visitor.
Bootstrap is undoubtedly the most widely used framework. Joomla's backend is based on it. Developed by Twitter for use on their web and in their backend. http://getbootstrap.com
One of our favorite framework as it is extremely fast to develop with. Many of our projects have been made in this framework. https://getuikit.com
A highly advanced and well-framed framework that is updated at a very high rate. http://foundation.zurb.com