Almost all current premium themes, let alone the frameworks carry some system of button creation very useful for contact pages, sales, etc. Now, the problem is that you create a dependency on the topic because they are usually generated by shortcodes own of the subject you're using, and that will stop working if you change the subject .
So the best solution is a plugin, which will generate buttons at will, and with the design you specify at every moment, regardless of the theme you use.
One that Forget about shortcode buttons that, once active, is integrated into the WordPress editor and allows to insert any type of fully customized buttons in any entry or page in texts , colors, shapes, shadows, whatever you want.
There is nothing to configure previously, simply where you decide to insert a button you give the icon that adds to the editor's format bar and opens the interface to create it and inserts it . Create the buttons using the latest CSS techniques and you can even add icons Dashicons or FontAwesome .
Is not it clear to you? Well here you have some captures and a video that show it wonderfully, you will see that it has no mystery whatsoever and it is very, very effective and easy to use.