I recommend the book First Things First.
Not everyone has a knack for using a day planner and even using the paraliminals Get around to it or Automatic Pilot don't win if we always find ourselves handling the things that suddenly come up that are urgent.
That book gives you an idea or what you need to look at and prioritise so that you give time to the important things that often get overlooked during our day until they become urgent or lost.
Also give the Paraliminal Anxiety Free a shot if you have it. Part of the reason we put off doing things we know we should be doing is because they either overwhelm us or are giving us some sort of anxiety about doing them (how long it's going to take, getting it right, not having everything you need, another task associated with it that needs to be addessed?)
Alex