Try to follow the rule "Only handle it once," i.e. if you're picking up stuff, pick up one item and put it away, then pick up the next.
Don't try to do bunches of complicated little tasks all at once. Take a moment to feel satisfied when a task is done; don't jump right to the next one.
Carry an index card and pencil in your pocket. Make notes of things that need to be done and check them off. Any other memory bits can also be written down.
Prime your visual memory. When you move an object to a new place, take a moment to look directly at it and say "Here is where I put the Xxxxx."
Take advantage of quality online cognitive tests, such as those from Mayo and AARP.
Participate in interesting online groups like this one!