Let's discuss strictly technical details of icon design
1. Lines, angles
One of the vital elements of the image is the outline of the object, i.e. rough border, which separates the object from the background. When designing normal-sized images, the designer occasionally thinks about highlighting of objects with complementary outlines. This is unnecessary because of the scale: even low contrast objects do not blur into a single whole. Icon graphics is different. Two variants are available: either object and background colors have to be from opposite sides of the color wheel, or the object should be divided from the background by contrast lines and shadows. I would like to dwell on lines deeper.
If we think more to the large scale graphics, we can note that in order to highlight edges, we can use any (including the most complicated) angles, Bezier curves and edges. Anyway, the line will look ideal thanks to anti-aliasing. When shrinking the image dimensions to the small icon size, situation changes greatly. When each particular pixel is equally important and can change the whole appearance of the icon, anti-aliasing is just unreasonable. It comes that you have to consider the possible line angles.
The slope 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 accuracy and esthetics.
For example, a 18-degree slope consists of many small 3-pixel lines combined with a 1-pixel downshift:
This is how nearly every line looks like. Basic element followed by joining and second primary element. However, not every slope makes the line look neet and not annoying.
For example, here are 25 and 20-degree angles:
It can be easily known which line is more appealing. The 25-degree angle makes a line consisting of even 2-pixel basic elements. The 20-degree angle has a primary element containing of three lines: 3-pixel, 3-pixel and 2-pixel. The slope is more complex, thus, when not combined by additional visual effects, it brings a feeling of messiness: the primary elements have contrast which is too obvious to hide from the human sight.
Now we can see the first rule. The most "correct" slopes must make as simple basic elements as possible. Thus, the ideal slopes are 0 and 90 degrees. In them, 1-pixel basic elements are joined without downshift and produce smooth lines. Less perfect are slopes which form basic elements of 1, 2, 3 pixel with 1-pixel downshift. Surely, the lines can not be smooth, but the human brain will process the image and present to the viewer what you intended to show to him. Also, the mentioned angles can be considered acceptable (but at a stretch): angles with basic elements made of different lines shifted by more than 1 pixel.
It is the time to move to another issue. In the last paragraph, I purposely defined angles with basic elements of 1, 2 and 3 pixels as acceptable. Such small lines, especially when a great number of them is joined, appear as solid. But what happens if we change the primary elements to 10 or 20 pixels?
Here is an example:
It can be clearly noticed that the line loses its solidness. 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 have the second conclusion: if you use minimal slopes, which produse long basic elements, it must be reasoned and used with maximum caution.
And, finally, the third thing I wanted to tell about lines. I already wrote that the primary element should be as plain as it can.
For instance, a 25-degree angle can be produced in the two (of course more of them exists) following ways:
In the first case the basic element is a 2-pixel line. In the other picture, it is made of three lines: 3-pixel, 2-pixel and 1-pixel. The same slope but the look is different. The complex basic element made the line messy.
Such examples can be made for almost any slope, so in your works, try to simplify everything.
It can be stated without an overstatement that the color is the main aspect of your work; not suiting or poorly matched colors can ruin even the most creative idea. What can we write about the color in icon graphics?
First, there is a clear rule: if the picture looks poor when converted to monochrome, then the colors that were used are wrong. This rule is valid not exclusively for icons but for the whole graphic design.
Second, you will probably unable to use common RGB. Sure, you may use internet colors only, but this ties you hand and foot. Gradients, shadows, blending and many other effects will not be available to you.
Third, try to increase the portion of "plain" color. The more evenly colored parts without diffusion and jumps your picture has, the more clear it looks. Pictograms are too tiny and the over usage of complex effects makes the picture look dirty.
Fourth, gradients. This is a great instrument which can improve the appearance of any composition. Besides visuals, gradients are an ideal way to get rid of the "broken line" look (lines with too long primary elements). But be careful when applying them because too much gradients can ruin the flat color, and be not suitable for the gif palette.
Fifth, shadows and flares. All aspects of applying shadows and highlights in icon design are totally the same to the aspects of the overall graphic design. The only ine I would like to note: draw everything yourself. Don't use effects, make all shades and highlights in a separate layer and after that edit its transparency. When applying effects, you almost never know what the result will be. It is bad when you don't control the making of a project. It is worse if you don't control it if creating miniatures.
And, lastly, sixth. Nuancing is the main detail of icon creation, which largely results the visual look of the composition. If 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 is indifferent that the human eye never has this color; in the first case it will appear like a gray dot, but in the second one it will really be a blue eye.
Thoroughly control the picture, do not allow the optical tricks to ruin your work. It is acceptable if something is not perfect from the technical point of view, but the whole picture must be flawless.
As an example, I pictured the pack of juice standing in front of me. The image has plain color, gradients with broken lines, shadows and flares and nuances.
If I talked about something other than miniature creation, this chapter wouldn't fit into an entire book, but the size of images ;limits fonts too.
The size of letters becomes the main issue as opposed to their beauty. Nearly in all cases, unless the letters are the main part of the project, the font size has to be decreased to the greatest extent possible.
In general, almost any graphic company has its own font with little letters. This font can be created in a couple of hours. You can browse the internet and collect your own collection of very nice fonts. First of all, I would recommend you to download the DS Pixel and Seventen 7Vedi webpage and the entire series of fonts from the Lakmus Lab website.
If you don't need a new font, little typesizes of Arial and Verdana will work. As a last resort, you can create the needed characters yourself.
There are not many rules there. First, letters cannot be less than 5 pixels high or less than 3 pixels wide.
Second, letters cannot use anti-aliasing. It turns the font into an incomprehensible set of pixels.
However, there are no rules without exceptions and the 5-point Arial looks perfectly readable.