Empty all of the "to-do's" in your head onto a piece of paper -- and keep this MASTER task list close at hand so you can add items as they occur to you.
Leave room on your DAILY task list for chores off of your master task list, scheduled appointments, and urgent items that just pop up.
Limit your daily task list to no more than ten ITEMS you hope to complete during the day -- with no more than two large or difficult tasks.
Create an AGENDA for your daily task list, scheduling times for completing specific activities whenever possible.
As you look over your "to-do" list, ask yourself if each task is NECESSARY, if it has to be done by you, and could it be simplified in any way.
If you tend to wait until the last minute to complete a task, create artificial DEADLINES to motivate yourself to finish a task early.
Understand your work STYLE -- whether you like to work in short bursts or long stretches -- and high and low-energy periods, and schedule your day accordingly.
Make liberal use of MEMORY joggers -- a list of things to take with you to a meeting, an alarm clock to remind you of an appointment, etc.