its always a good idea to write down notes and it is something I've made a habit of in the past few weeks. if you're not ready to get fully organised with planners etc, then short notes/lists are perfect for you. I would usually start writing notes the night before, the notes will contain tasks I need to get done for the following day and by writing them down it has somewhat allowed the ideas/tasks to remain fresh in my mind ready for the next day, I'm letting the ideas marinate in my head. Then I'd start the day knowing what to get on with, something I always like doing is completing the easier tasks first as I like the satisfaction of having completed something within the day.
So to keep things simple, write notes!