Let's discuss purely technical aspects of icon creation
1. Lines, slopes
One of the most important parts of the image is the outline of the object, i.e. rough border, which limits the object from the rest of the image. When working with normal-sized graphics, the designer rarely cares about defining objects with additional outlines. This is unnecessary because of the scale: even non-contrasted objects do not blend into a one. Icon graphics is different. Two solutions are available: either foreground and background colors must be from opposite sides of the color wheel, or the foreground must be divided from the background by contrast lines and shadows. I will dwell on lines deeper.
If we return again to the large scale graphics, we can note that in order to define contours, we can use any (including the most complex) angles, Bezier splines and borders. Anyway, the line will look perfect thanks to anti-aliasing. When shrinking the image dimensions to the small icon size, situation changes dramatically. When every single pixel is equally important and can change the overall appearance of the composition, anti-aliasing is just not applicable. It comes that you have to consider the possible line angles.
The slope you choose for the line, specifies the step for this line. This means that every line is made of basic elements, the combination of which defines its accuracy and visual appeal.
For instance, a 18-degree angle consists of many tiny 3-pixel lines combined with a 1-pixel downshift:
This is how almost each line looks like. Primary element with joining and second basic element. However, not every slope creates lines that look look neet and not annoying.
For example, look at 25 and 20-degree slopes:
It can be easily seen which line is more appealing. The 25-degree angle produses a line consisting of equal 2-pixel basic elements. The 20-degree slope has a basic element consisting of three parts: 3-pixel, 3-pixel and 2-pixel. The angle is more complex, thus, when not combined by additional visual effects, it creates a feeling of untidiness: the primary elements have contrast which is too strong to hide from the human sight.
Here we can come to the first rule. The most "appropriate" slopes have to make as plain basic elements as they can. therefore, the ideal slopes are 0 and 90 degrees. In them, 1-pixel primary elements are joined without any shift and form even lines. Less perfect are angles which form primary elements of 1, 2, 3 pixel with 1-pixel downshift. Surely, the lines can not be even, but the human sight will process the image and provide to the user what you intended to show to him. Also, the mentioned slopes can be considered correct (but at a stretch): angles with primary elements consisting of different lines shifted by more than 1 pixel.
It is the time to move to another problem. In the previous paragraph, I intentionally defined angles with primary elements of 1, 2 and 3 pixels as acceptable. Such small lines, especially when a great amount of them is joined, look like solid. But what do we see if we change the basic 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 continuous line anymore; it is a set of different lines, situated near one another. Rarely any designer wants its composition to look inconsistent. Thus, we come to another rule: if you use small slopes, which make long primary elements, it must be justified and employed with maximum attention.
And, finally, the last aspect I have to tell about lines. I already wrote that the basic element has to be as simple as it can.
For example, a 25-degree angle can be produced in the two (of course more of them exists) following ways:
In the first case the primary element is a 2-pixel line. In the other picture, it is made of three elements: 3-pixel, 2-pixel and 1-pixel. The same slope but the image is different. The complex primary element produced the line untidy.
Such examples can be made for about any angle, so in your projects, make sure to simplify as much as possible.
It can be stated without an exaggeration that the color is the main aspect of your work; improper or poorly balanced colors can kill even the best idea. What can we write about the color in miniature graphics?
First, there is a clear rule: if the image looks poor when reduced to monochrome, then the colors that were chosen are incorrect. This rule is true not exclusively for icons but for the entire graphic design.
Second, you will probably unable to use safe RGB. Sure, you can use internet colors only, but this ties you hand and foot. Gradients, shadows, dithering and many other tricks will not be accessible to you.
Third, try to enlarge the areas of "flat" color. The more consistently colored areas without blurring and jumps your picture has, the more clear it appears. Icons are too tiny and the excess usage of special filters makes the picture look dirty.
Fourth, gradients. This is a great instrument which can change the look of any composition. Other than esthetics, gradients are a perfect 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 not suitable for the gif palette.
Fifth, shadows and flares. All rules for using shades and flares in icon creation are completely the same to the aspects of the general graphic design. The only thing I would like to mention: draw everything by hand. Don't use filters, make all shadows and flares in a different layer and then edit its transparency. If using effects, you rarely can predict what will it look like. It is bad when you don't control the making of a project. It is worse if you can't control it when drawing icons.
And, lastly, sixth. Nuancing is the main aspect of icon creation, which greatly results the esthetic appearance of the project. When the blue human eye in the icon is sized 1 pixel, increase the color saturation. For instance, instead of 0, 131, 159 make 71, 195, 242. It is indifferent that the human eye never has this color; in the first case it will look like a gray dot, but in the second example it will really be a blue eye.
Thoroughly control the picture, do not let the optical tricks to spoil your work. It is OK if something is not perfect from the technical point of view, but the entire composition must be perfect.
As an example, I pictured the pack of juice located in front of me. The picture has flat color, gradients with broken lines, shades and highlights and tints.
If I talked about something other than pictogram creation, this part wouldn't fit into an entire book, but the size of images ;limits fonts too.
The resolution of symbols is the leading issue as opposed to their look. Nearly in any case, unless the letters are the main part of the image, the text size has to be reduced to the largest extent possible.
In general, almost any graphic studio has its unique font with little letters. Such a font can be crafted in several hours. You can browse the internet and make your own collection of very nice fonts. Primarily, I would recommend you to get the DS Pixel and Seventen 7Vedi website as well as the whole series of fonts from the Lakmus Lab website.
If you don't want a new font, tiny typesizes of Arial and Verdana will work. As a last option, you can draw the needed letters yourself.
There are quite a few rules there. First, characters 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 unrecognizable set of pixels.
Though, there are no rules without exceptions and the 5-point Arial appears perfectly readable.