Tips for correctly addressing an envelope for easier mailing include using all capital letters, no punctuation and black ink on white paper. Other tips entail not omitting directionals such as "East" and "West" and taking the time to include an apartment number or correct ZIP code.
An address should always have the attention line on top of the other information and never below the city and state or at the bottom. This is because mail processing machines read addresses from the bottom up; if a machine finds an attention line or other information such as a logo or slogan in the wrong place, it may get confused and incorrectly route the mail. Using this principle, if an apartment number or suite number cannot fit on the same line as the delivery address, the number needs to go on the line above the delivery address instead of the line below.
For addresses printed from a computer, fonts should be at least 10 point, simple and left justified. One space should separate the city and state, while two spaces should separate the state and ZIP code. There should be no reverse type, such as white ink on a black background. Address labels should not truncate or cut off information.