Perhaps the most important function of any icon is to inform the user. Wether it’s telling the user what a particular button or menu does or communicating the function of an app, having a clear and informative icon will give users a sense of comfort with a product. Sometimes you’ll have to get creative, but in most cases it’s best practice to use imagery that’s already familiar.
Using Familiar Imagery
Look around at some of the icons you see everyday, like a camera which denotes taking pictures, or a speech bubble for chatting. It can be tempting to reinvent the wheel, but when it comes to common tasks it’s best to see what’s commonly used. Of course you should bring your own style and design language to the iconography, as long as it still evokes the correct imagery.
However, concepts like sharing are visually represented differently depending on the platform or operating system. Platform-specific iconography can get confusing, especially if you’re designing for a cross-platform product. It’s best practice to taylor these icons for your users. An Android share icon is confusing to iOS users, and vice versa.
For concepts that may not have a standard visual representation, finding something that fits and clearly communicates a concept can be difficult. The best thing to do is start by looking at something that’s analogous to the function in the real world.
A vital part of this process is testing. I often test my concepts on friends and family to see if they can intuit what the icon might do and refine the idea based on that feedback. When you do this you should ask “what do you think this does” rather than asking wether it relates to a particular function as that will affect the feedback you get. Leaving it open allows the most honest feedback, and thusly gives you a better idea of whether your idea is good or not.
Design Without Text
The best icons can communicate their idea without text. Icons are often used in tandem with text labels, such as apps, or certain UI functions, but you should design as if the icon will be presented without text. Designing icons with optimal visual clarity will allow users to understand and identify the meaning that you’re trying to communicate with a simple glance.
Humans are very visual by nature. After a while most people can train themselves to ignore text labels on icons. Think about the home screen on your smartphone, you probably pay more attention to the icons when identifying the app you want to open.