Avoid:
Italics, or a type that changes the normal form of the letters. These make reading more difficult.
BLOCK LETTERS SHOULD BE AVOIDED AS WELL. THIS FORMS A DENSE BLOCK OF TEXT THAT CAN TIRE THE READER. IT ALSO MAKES IT MORE DIFFICULT FOR THE READER TO RECOGNIZE THE SHAPE OF THE WORDS.
Words printed in lower case have more distinctive shapes than words printed in UPPER CASE.
Use:
Serif fonts because they are easier to read. They can also be bolded to highlight important information. Examples of serif fonts are: