Send reminders to yourself on your cell phone if you check voicemail or text messages often. Email prompts to yourself, as well, so they'll be waiting in your inbox when you get home. Only delete the message once you've completed the task.
Tape large or brightly-colored notes to your keys, steering wheel or the front door where you can't miss them. If you're prone to leaving projects, letters to mail or your lunch in the house, for example, the reminders will stop you before you leave the house.
Complete tasks as soon as you think of them rather than telling yourself you'll remember them later. If you're watching television, for example, get up immediately to put the wash in the dryer, add an item to your calendar or ask for tomorrow's lunch money instead of waiting until the next commercial break.
Use mnemonics when trying to remember a list of items or important terms for school. Simply turn the first words or letters into a word, silly phrase or song. A common one is using the fake name "roy g biv" to remember the colors of the rainbow (red, orange, yellow, green, blue, indigo, violet).
Leave visual memory triggers to remember things you need to do. If you have to mop the kitchen floor first thing in the morning, for example, just leave the bucket and polish in front of the refrigerator door.