What do you need to take into account in order to create an icon?

Despite what it seems, creating an icon is not an easy job. There is a long and complicated process behind every single icon, where every designer has to follow some basic rules in order to have excellent results. There is no right or wrong way to get started in the Icon Design industry, but there are some steps you shouldn't miss in order to get better results.
Just like in any other piece of art, is very important to draw sketches. Sketching not only let us put our ideas into paper, but it also gives us the opportunity to check if what we had in mind can actually work when it's on paper. When we sketch, we unconsciously decide a few of the characteristics of our design, such as perspective. During this process, it's important to have in mind a Graphic Metaphor.

A Graphic Metaphor is created by the encounter of two elements that usually wouldn't go together, but can represent a concept. Defining a Graphic Metaphor is one of the key steps to succeed when designing an icon. It also helps to achieve visual unity, a very important property of successful projects. Remember, sometimes it's better to use a well known graphic metaphor than to invent one that doesn't communicate what we need.
Here's an example of a Graphic Metaphor. As you can see, dying trees are represented with blood, which makes us infer that rain forest disappearance is attached to humans disappearance.

Caption: Half of the world's rainforest have already died. If the rest go. So will you.

When you're sketch is ready, all the details in place, and you already think it would make a good icon you can start creating it in your desired software (Illustrator or Inkscape are two great options). When you're creating the icon on your computer, you must be attentive to details, shadows, light, perspective and colors. Be aware that every single one of this aspects needs to contribute to the icon. Icons can communicate a message through an image, text, or both. If we're only going to use an image, we must make sure it's meaning is clear enough, and if we are going to use text, we need to make sure it's not part of the graphic, that way it won't be deformed when scaled, or unreadable when the icon gets to small.

When you're creating an icon, make sure you know who your target is. Is not the same to design for children, young people, women, people from South America, Europe or the United States. Designs are often influenced by religious views and traditions.

Try not to put many elements in your icon. If you're designing it in a large size, it would probably look fine, but remember an icon must be scaled and it has to work in every single needed size. If you put a bunch of useless elements it would certainly fail at communicating the idea and besides, it will look bad. If you're planning on creating a set of icons, you have to be very careful to maintain visual unity and at the same time make then differentiable. Turbomilk shows us this example:

So, we need to:

* Sketch.

* Use a Graphic Metaphor.

* Define a target audience and make sure the image you designed communicates the idea you have in mind to that specific target.

* Make as much details as you need, as long as it doesn't make the picture unclear.

* Maintain a visual unity, using similar colors, lightning, perspectives and shadows.

* Scale your icon and make sure it works in all sizes.

With this simple steps you can start thinking of creating your own icons, however, if this is too complicated, or you don't have many ideas on your mind, you can always look for the experts when it comes to icon design.