Choose a topic on which your encyclopedia will focus. As there are hundreds of general information encyclopedias, the more specific your topic is, the better. For example, rather than simply writing about sports or even American football, it would be better to focus on a specific aspect of American football such as the defense, offense or special teams, or a position such as linebacker, quarterback or wide receiver, or even a team such as the Cardinals, Giants or Steelers.
Identify the experts of your specified topic. These will include people ranging from academics at a university to journalists to aficionados. For example, if you want to write an encyclopedia on the Pittsburgh Steelers, you might identify people such as former players, news reporters that cover the team, announcers that work at the game, and season ticket holders. Identify as many experts as possible.
Request your identified experts to submit to you a list of the most memorable features of your selected topic as possible. Select a maximum number of features you want your experts to identify, probably between 25 and 100. For example, for a Steelers encyclopedia, you might ask experts to name the 50 most memorable things about the Steelers.
Compile a master list of potential subjects out of all the experts' submissions. Log the frequency with which some subjects are repeated.
Research the most commonly repeated subjects first to create your entries. For example, for a Steelers' encyclopedia, you may wish to research and write the entry for "The Immaculate Reception" before you research and write the entry for "William Gay."
Compose your entries. You can choose to format your entries however you like. Some encyclopedias require longer entries ranging from 1000 to 2000 words, while other encyclopedias only ask for 300 to 400 words per entry. All encyclopedia entries should contain basic journalistic information; this means writing an entry that appropriately, sufficiently and concisely provides information to the "five-Ws": who, what, where, when and why.
Alphabetize your entries to make it easy to navigate your encyclopedia.