To memorize all 50 states, group them into regions, and create mnemonic devices for each region. For example, to memorize the western states of California, Oregon and Washington, place the first letter of each state's name in order from south to north to spell the word "COW."
Another trick is to take part of the name of a state and use it to describe its location. For example, the state of Connecticut connects Massachusetts to New York. Another option is to use something memorable about the state, such as the bottom of Nevada has a "v" shape, and the letter "v" is in the middle of the name. Puzzles and word play make memorizing the 50 states fun and easy as well.