The usage of icons is a great complement. Displaying icons could make navigating through your website more user-friendly for your visitors. And it could make your site look prettier.
The WordPress Menu Editor allows you to easily create menus for your website. But unfortunately it is not possible to add an icon to a menu item. Adding this functionality could be a challenge if you’re not a experienced developer.
But as you will have gathered there is a Plugin for every need. The free Menu Icons Plugin maybe is exactly what you are lokking for. After activation you are able to add an icon to a menu item inside the WordPress Menu Editor. There are a lot of nice icon sets included. You can place the icon before or after the menu item, define the size and set the alignment.
The Plugin works with every Theme that uses the WordPress Menu System.