In scientific illustrations, the visual composition should guide the viewer along a simple and logical grid arrangement in order to overview the most important information and easily enter the image. The top-left corner is the natural entry point for viewers and most of them expect a left-to-right and/or top-to-bottom pattern of eye-scanning. A wide variety of compositional designs are possible in a figure to accomplish the desired flow of information. The specific layout of a figure varies depending on the content, the number of sections and the relationships between the parts and the whole.
Use visual contrast to highlight the most important information. Avoid the following mistakes often introduced in illustrations: lousy images, improper transparency/translucency effects, artifacts, raster graphics, etc. Vector-image programs should be used. Vary the size, shape, position, orientation, or color of the different elements in order to make the key part most prominent. Larger, darker, and brighter elements are more conspicuous than smaller, lighter, and duller ones. Avoid incorporating too much forms of visual contrast. A single type of contrast (shape, size, color, etc.) is sufficient. Excessive contrast creates visual noise that obscures information. Abstain from using too many colors and maximize the contrast between the different sections and the background. Do not combinate complementary colors because this causes visual vibration. Sometimes, it is preferable to use a black-and-white palette rather than a full color one. High-contrast black and white illustrations are often more readable than color ones and they are better for copying and laser printing. The text should be readable after the drawing has been resized to its final dimensions. Most publications use serif typefaces for text while sans-serif types are used in figures.