A mnemonic is a device, such as a jingle or a rhyme, used to aid memory. Music students remember "Every Good Boy Does Fine" to remember the notes "EGBDF" from bottom to top in the treble cleff. Grade school students learn mnemonics to master spelling (e.g., there is A RAT in "separate"). Medical students, who must memorize large amounts of anatomical information, use many mnemonics that are passed like prized poetry among students. You probably know many mnemonics.
The mnemonics in these examples are specific to particular bits of information. Learning the mnemonic to read music doesn't assist you in learning to spell. Other mnemonic devices have general application, and are the key to memory improvement. These are more difficult to master and require practice, but make it possible to learn dazzling amounts of information.
The first step in mastering mnemonics is to understand your own mind. Think of a type of thing that you remember well. Most people have strongly visual memories, recalling scenes from movies vividly. Think of your favorite movie, one that you have seen a number of times. What is the most memorable moment? It might involve dialog, action, or music as well as a visual image. That scene is easier to remember than a telephone number, isn't it? Other people remember poetry or music (sounds) better than visual images. It doesn't matter what sort of thing you remember well, as long as you figure out how your own mind works.
The next step in mastering mnemonics is to figure out how to translate information that has no particular significance to you (a telephone number, for example) into something that you care about.
Here is a basic mnemonic device used by Dr. Wilson: the translation of numbers into letters.
Each digit from zero to nine can stand for a letter.