• Visual contrast of colour between foreground and background features (contrast ratios)
• Objects should contrast with their surroundings
• E.g. Use a contrast ratio greater than 7:1 for text less than 7 points
• Select color pairs that accommodates different types of color-blindness, e.g. Red and blue for red-green blindness
• Use colours with strong contrast and supplemental visual variables such as shape and size
• Sans serif is preferred over serif fonts
• Italics should be limited
• Generally, the higher the x-height in relation to a capital letter, the more legible the font is likely to be