Your goal is to create a poster that people can read and understand without difficulty. Important elements to consider are:
Please see below for more detail regarding font selection, style, size, and color.
Only use 2-3 font styles in your poster. For example, you could use one font style for your titles; another style for the text inside each block; and a different font for the labels to any illustrations.
Most people only use two font styles - one for headings and the second for the text. Good font combinations for heading/body text include:
Do not use script or decorative fonts, because they are hard to read.
Fonts generally come in two styles: serif and sans serif:
Many people select a sans serif font, like Futura, for the title/section headers, because the letters are clear and stand out. Serif fonts, like Garamond, are used for the text inside the box, because it is easier for people to read.
Text size should be large enough so that people can read it from 3-5 feet away. Common sizes for different text elements are:
Do not make text size smaller than recommended sizes in order to squeeze more information into your poster. Rewrite, replace with an illustration, or delete if you cannot make text fit onto the poster at the recommended sizes.
A good rule of thumb to use when determining if your poster will be readable is to print it on a 8.5 x 11 piece of paper, set it on the floor, and try to read the text while standing over it. If you can, the text is probably the right size.
Always select font colors that have a high contrast with the background. Beware of colors that are too harsh to read, which can limit legibility.
Font color can be used to connect ideas and sections and to make ideas stand out. Aim for simplicity and do not use more than 2-3 colors.
Download the free Colour Contrast Analyser to check color contrast.