I don’t often recommend sticky notes as organizing tools, however there are times these can help. One time they’re useful is when you need to remember to take something with you when you go out. If your door doesn’t support a magnetic clip, place a sticky note on the door where you can’t miss it when leaving. If the note pertains to an errand you need to remember, simply take it with you. If it reminds you to do something before leaving, such as turning on the dishwasher, you can do that and your dishes will be clean when you return.
So, have a supply of brightly coloured sticky notes handy (the pale yellow ones may blend into the décor and be missed) so you can create the reminders you need. You may even colour code-orange for dry cleaning, teal for library books to return, green to remind you to go to the bank, etc.