Serif fonts should be used for body text, and sans serif for headings. This is not a hard and fast rule, but a helpful one if you are trying to decide how to format.
Do not use many fonts--this is confusing and can look messy.
If you need more differentiation, consider bolds, italics, underlines, or changing the weight of the font.
Some people have difficulty reading the letters on a page. Making good font choices can help make it easier for them to read.
Sans serif fonts seem less crowded.
Larger font sizes should be used, at least 12-14 pt.
Leave extra white space around elements, like headers and paragraphs--it makes it easier to separate out text.
Good basic fonts for dyslexia, according to a study, are:
Helvetica
Courier
Arial
Verdana
Computer Modern Unicode
Use Google Fonts to find and download fonts that best suit your needs.
💡 GRIDBit: "Serif" indicates the small "feet" of text. Therefore, "sans serif" fonts are slightly simpler in style. Sans serif used to be preferred for screen-based text due to the low resolution, but this is not as much of a problem with modern screens.
Body Text: Four Important Considerations. Practical Typography.
Dyslexia Friendly Style Guide. British Dyslexia Association.
Good Fonts for Dyslexia. Luz Rello and Ricardo Baeza-Yates, Universitat Pompeu Fabra, 2013.