When you are writing your to-do list, keep a four-colour multipen handy and use its colours to make a visual, systematic list. Productivityist's Mike Vardy describes a colour-coded system for capturing tasks on paper, which you could easily replicate on a whiteboard.
Heres's how Vardy does it:
Here's what each colour represents:
Green: Things that are associated with professional work or development. A lot of these tasks are "heavy lifting" items, and they will require greater deal of will to make sure that they're done right...and not just done.
Orange: Things I capture using this colour involve a more personal — or deeper — connection. So it's no surprise that I generally write family-oriented or personal tasks down in this colour. (Orange has been proven to enhance concentration and focus, so using it has proven to be a really prosperous choice.)
Blue: I use blue for the items that don't fit into any of the above. Since blue is perhaps the most commonly used in colour, using it for this purpose seems like a natural fit. It doesn't stand out like the others do, but it isn't exactly hidden either.
Black: This colour is used during the processing of my captured items. Nothing gets written down in black, but strikethroughs, arrows, and contexts do. Black signifies an "end" for me, so by using it I know that I have finished what was needed to be finished during the capturing and processing phase of my task management workflow.
Vardy also uses the same colours for his calendar to mark events, appointments and activities. It's often useful sort your to-do list by energy levels or by emotion, and you could look at combining those ideas with Vardy's system.
How Colour Can Help You Get the Right Things Done [Productivityist]