[overstep]

While preparing a To Do list I use additional colors: green for the time and red for the priority. Sometimes I also draw green and red bars instead of just writing the numbers. It's good to actually see it, that way the truth is clearer. If a task takes three chunks then I draw three bars in one line and mark them separately when they are done.
I also did a permanent list of tasks that I do almost daily, I did it on a spreadsheet, sorted by priority and added a graph. The funny thing is that the most important tasks take the least time for me, they are planning an visualizing. I often skip long tasks if they are not vital along with the saying "There is never enough time to do all very important things, but there is always enough time to do the most important things". There are also tasks that seem long and not vital but they are definitely good an have effect on everything else, one example is a walk in the park.