Stop writing notes on post-its and loose paper.  Get a little dry erase board to put on the fridge, at the back door or anywhere convienent for you and write notes and lists on there.  Once you have completed something, just wipe if off.  Most of the boards are magnetic as well so you can hang newspaper clippings, business cards, etc to keep things organized for the week.  And if you keep your grocery list on the board then when it is time to go shopping just write it on a piece of paper, instead of trying to remember where you left the list you started the other day. 

Another place to start lists and write notes is on the bathroom mirror with a dry erase marker.  It is so easy to keep one in the drawer and in the morning when you are getting ready or at night if you have an idea then just pull out the marker and write it on the mirror.  And once you are done, it just wipes right off.  This can also help keep kids organized because they can write their weekly activities on their mirror and know what they have going on each day of the week.  As the week goes on they can erase what they have done.