As a general rule, capital letters are most easily recognized, but tend to be read individually. Lower case letters, on the other hand, are generally read as whole words or phrases.

Sign design research designates six type styles as the most basic:

For the most part, reliance on the last four of these can be a problem. People are not used to reading these fonts for extended periods of time. Use them sparingly, if at all.

Capital and lower case letters, with the exception of script styles, are generally equally legible. As a general rule, the width of a letter's horizontal stroke should be approximately 1/5 of its height.

In choosing numerals, it is generally accepted that Roman numerals slow readers down, because they are more complex and less familiar to the viewer than Arabic numerals.