Let's discuss purely technical details of icon design
1. Lines, slopes
One of the vital parts of the composition is the outline of the object, i.e. rough border, which limits the object from the rest of the image. When creating normal-sized images, the designer occasionally thinks about highlighting of objects with complementary lines. This is not needed because of the size: even low contrast objects do not mix into a one. Icon graphics is different. Two solutions are possible: either object and background colors have to be from opposite sides of the color wheel, or the object should be separated from the background by contrast lines and shadows. I will discuss lines in more detail.
If we return more to the large scale graphics, we can note that in order to highlight edges, we can use any (even the most complicated) angles, Bezier curves and edges. In any case, the line will appear perfect due to anti-aliasing. When decreasing the graphic dimensions to the small icon size, situation changes dramatically. When every particular pixel is equally important and can ruin the overall look of the composition, anti-aliasing is simply not applicable. It comes that you have to think about the possible line angles.
The angle you select for the line, determines the step of this line. This means that each line is made of primary elements, the combination of which defines its neatness and esthetics.
For example, a 18-degree angle contains many small 3-pixel lines connected using a 1-pixel downshift:
This is how nearly each line looks like. Basic element followed by joining followed by second primary element. Unfortunately, not every slope creates lines that look look attractive and not messy.
For example, here are 25 and 20-degree angles:
It can be easily seen which line is more appealing. The 25-degree angle produses a line containing equal 2-pixel basic elements. The 20-degree angle has a basic element consisting of three parts: 3-pixel, 3-pixel and 2-pixel. The angle is more complex, therefore, if not supported by other visual effects, it creates a feeling of messiness: the basic elements have contrast which is too strong to escape the human sight.
Here we can come to the first conclusion. The most "appropriate" angles have to make as plain basic elements as possible. therefore, the ideal slopes are 0 and 90 degrees. In them, 1-pixel basic elements are combined without downshift and produce smooth lines. Less perfect are slopes which form primary elements of 1, 2, 3 pixel with 1-pixel downshift. Of course, the lines will not be even, but the human brain will process the image and present to the user what you intended to show to him. Also, the following angles can be considered correct (but at a stretch): angles with basic elements made of unequal lines shifted by more than 1 pixel.
Now we can touch another problem. In the previous paragraph, I purposely defined slopes with basic elements of 1, 2 and 3 pixels as correct. Such small lines, especially when a large amount of them is joined, look like a single whole. But what happens if we change the primary elements to 10 or 20 pixels?
Here is an example:
It can be clearly seen that the line doesn't have integrity. It is not a single line now; it is a set of different lines, located near each other. Rarely any artist wants its composition to look that way. Thus, we come to another rule: if you use minimal slopes, which make long basic elements, it must be reasoned and employed with great attention.
And, finally, the last thing I have to tell about lines. I did write that the basic element has to be as plain as it can.
For instance, a 25-degree slope can be produced in the two (of course more of them exists) following ways:
In the first picture the primary element is a 2-pixel line. In the other case, it is made of three lines: 3-pixel, 2-pixel and 1-pixel. The same slope but the image is different. The complicated basic element produced the line messy.
This examples can be produced for almost any slope, so in your works, make sure to simplify everything.
It can be said without an exaggeration that the color is the main element of your work; improper or badly balanced colors can ruin even the most creative idea. What can we say about the color in miniature graphics?
First, there is a clear rule: if the picture looks bad when reduced to grayscale, it means the colors that were used are incorrect. This rule is valid not only for icons but for the entire graphic design.
Second, you will probably unable to apply common RGB. Sure, you may select internet colors only, but this ties you hand and foot. Gradients, shadows, dithering and many other tricks will not be available to you.
Third, try to increase the portion of "plain" color. The more evenly colored parts without blurring and jumps your picture has, the more neat it looks. Icons are too small and the excess usage of complex effects makes the image look messy.
Fourth, gradients. This is a great tool which can change the look of any composition. Other than esthetics, gradients are an ideal way to get rid of the "broken line" effect (lines with too long primary elements). But be careful when applying them because too much gradients can kill the plain color, and be unable to fit into the gif palette.
Fifth, shadows and flares. All aspects of applying shadows and flares in icon creation are totally identical to the aspects of the general graphic design. The only ine I have to mention: draw everything by hand. Don't apply effects, make all shades and flares in a separate layer and after that edit its transparency. When using filters, you almost never know what will it look like. It is bad when you don't control the process of creating of a composition. It is worse if you can't control it when creating icons.
And, finally, sixth. Tinting is the main aspect of pictogram creation, which largely results the esthetic appearance of the project. If the green human eye in the picture has the size of 1 pixel, increase the color intensiveness. For example, instead of 0, 131, 159 make 71, 195, 242. It doesn't matter that the human eye can't have such color; in the first case it will look like a gray dot, but in the second example it will really be a green eye.
completely control the image, do not allow the optical illusions to ruin your work. It is OK if objects is not consistent from the technical point of view, but the entire image must be perfect.
As an example, I pictured the packet of juice standing in front of me. The image has flat color, gradients with broken lines, shadows and flares and tints.
If I talked about something bigger than miniature design, this chapter wouldn't fit into an entire book, but the size of images restricts fonts too.
The resolution of symbols is the leading aspect as opposed to their fineness. Nearly in any case, only if not the letters are the main part of the project, the font size must be decreased to the largest extent possible.
In general, virtually any graphic company has its exclusive font with little characters. Such a font can be made in a couple of hours. You can search the internet and collect your own library of very nice fonts. Primarily, I would recommend you to get the DS Pixel and Seventen 7Vedi website and the entire set of fonts from the Lakmus Lab website.
If you don't want a new font, little sizes of Arial and Verdana will work. As a last resort, you can create the needed letters yourself.
There are not many rules there. First, letters cannot be less than 5 pixels high or less than 3 pixels wide.
Second, letters should not use anti-aliasing. It transforms the text into an incomprehensible set of pixels.
However, there are no rules without exceptions and the 5-point Arial appears perfectly understandable.