Let's consider purely technical details of icon making
1. Lines, angles
One of the vital elements of the composition is the framework of the object, i.e. solid border, which separates the object from the background. When working with normal-sized images, the designer occasionally cares about defining objects with complementary outlines. This is unnecessary because of the scale: even low contrast objects do not blend into a one. Pixel graphics is different. Two solutions are available: either object and background colors must be from opposite sides of the color wheel, or the object must be separated from the background by contrast lines and shadows. I would like to dwell on lines deeper.
If we think again to the big-size images, we can note that in order to highlight contours, we can use any (even the most complex) angles, Bezier curves and edges. In any case, the line will look perfect due to anti-aliasing. When decreasing the graphic dimensions to the small icon size, situation changes dramatically. When each particular pixel is equally important and can ruin the overall look of the icon, anti-aliasing is simply unreasonable. It comes that you should consider the possible line angles.
The slope you select for the line, determines the step for this line. Because every line is made of basic elements, the union of which defines its accuracy and esthetics.
For example, a 18-degree angle contains many small 3-pixel lines connected using a 1-pixel downshift:
This is how almost every line looks like. Primary element with joining and second basic element. Unfortunately, not every angle creates lines that look look neet and not annoying.
For example, look at 25 and 20-degree angles:
It can be easily known which line is more attractive. The 25-degree angle makes a line containing even 2-pixel primary elements. The 20-degree slope has a primary element containing of three parts: 3-pixel, 3-pixel and 2-pixel. The slope is more complex, thus, if not supported by additional visual effects, it creates a feeling of messiness: the basic elements have contrast which is too strong to hide from the human eye.
Here we can see the first rule. The most "correct" slopes must make as plain basic elements as possible. therefore, the perfect slopes are 0 and 90 degrees. In them, 1-pixel primary elements are joined without any shift and form even lines. Less perfect are slopes which form basic elements of 1, 2, 3 pixel with 1-pixel downshift. Of course, the lines can not be even, but the human sight will process the picture and present to the user what you meant to show to him. Also, the following slopes can be considered correct (but at a stretch): angles with basic elements made of different lines shifted by more than 1 pixel.
Now we can move to another issue. In the last paragraph, I intentionally defined angles with primary elements of 1, 2 and 3 pixels as acceptable. Such tiny lines, especially when a large number of them is joined, appear as solid. But what happens if we increase the basic elements to 10 or 20 pixels?
Here is an example:
It can be obviously seen that the line doesn't have solidness. It is not a single line now; it is a set of different lines, located near one another. Rarely any artist wants its composition to look inconsistent. Thus, we come to another rule: if you use minimal slopes, which produse long primary elements, it must be justified and used with great attention.
And, finally, the last aspect I wanted to mention about lines. I did write that the primary element should be as simple as possible.
For instance, a 25-degree angle can be produced in the two (sure more of them are possible) following ways:
In the first picture the primary element is a 2-pixel line. In the second picture, it consists of three lines: 3-pixel, 2-pixel and 1-pixel. The same angle but the look is different. The complicated basic element made the line messy.
This examples can be produced for about any slope, so in your projects, try to simplify as much as possible.
It can be stated without an overstatement that the color is the main aspect of your work; not suiting or badly matched colors can ruin even the most creative idea. What can we say about the color in icon graphics?
First, there is a certain rule: if the image looks poor when reduced to monochrome, then the colors that were selected are incorrect. This rule is true not only for icons but for the entire graphic design.
Second, you will probably unable to use safe RGB. Of course, you may use internet colors only, but this ties you hand and foot. Gradients, shadows, blending and many other effects will not be accessible to you.
Third, try to enlarge the portion of "flat" color. The more consistently colored parts without blurring and jumps your project has, the more neat it looks. Pictograms are too tiny and the excess usage of special effects makes the picture look messy.
Fourth, gradients. This is a great tool which can change the look of any picture. Other than esthetics, gradients are a perfect solution to get rid of the "broken line" look (lines with too long basic elements). But be attentive when applying them because too much gradients can kill the flat 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 identical to the aspects of the overall graphic design. The only ine I would like to note: create everything by hand. Don't apply filters, make all shades and flares in a separate layer and after that edit the opacity. If using filters, you rarely know what will it look like. It is bad when you don't control the process of creating of a composition. It is awful if you don't control it when drawing miniatures.
And, lastly, sixth. Nuancing is the main aspect of icon design, which largely affects the visual appearance of the image. When the green human eye in the icon has the size of 1 pixel, increase the color saturation. For instance, 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 appear like a gray dot, and in the second example it will really be a green eye.
completely control the image, do not allow the visual tricks to spoil your work. It is acceptable if something is not consistent technically, but the whole image must be flawless.
As an example, I pictured the pack of juice located in front of me. The image has plain color, gradients with broken lines, shadows and flares and tints.
If I talked about something bigger than pictogram design, this part wouldn't fit into a whole book, but the size of compositions ;limits fonts too.
The resolution of symbols is the main issue as opposed to their beauty. Nearly in all cases, only if not the letters are the primary part of the image, the font size has to be decreased to the largest extent possible.
In principle, virtually any design company has its own font with tiny letters. Such a font can be created in a few hours. You can browse the internet and collect your own collection of very nice fonts. Primarily, I advice you to download the DS Pixel and Seventen 7Vedi website and the complete set of fonts from the Lakmus Lab website.
If you don't need a new font, tiny sizes of Arial and Verdana will do. As a last option, you can draw the necessary letters yourself.
There are not many rules there. First, characters cannot be less than 5 pixels high or less than 3 pixels wide.
Second, letters cannot use anti-aliasing. It transforms the text into an incomprehensible mixture of pixels.
However, there are no rules without exceptions and the 5-point Arial looks perfectly understandable.