Addressing an envelope is a simple process requiring proper placement of a return address, delivery address and stamp. As long as these things are in their correct places, the letter is liikely to be delivered with no problems.
According to the United States Postal Service, writing the return and delivery addresses legibly is the most important step when addressing an envelope or package. The USPS asks that all addresses be written in either pen or legible marker and be readable from at least an arm's length away. All addresses should also be written on the same side of the envelope. The return address should be written on the top left of the envelope, the delivery address should be in the exact center and the stamp should be placed on the top right.
When writing addresses, the full address should be used. The address should cover three or four lines, although three is the preferred amount. The first line should have the person's full name. The second line should have the person's full mailing address with house/apartment number and street name. The third line should contain the city, state and zip code, but it is acceptable to list the zip code on the fourth line. The USPS also recommends using as few punctuation marks as possible, so commas and periods should be kept to a minimum.