The best advice I ever received about my task list was this: estimate how much time you need to complete the task. It changed my life and made my productivity much better.
It really is a simple behavior. When I write down the task, I try to estimate how long it will take. For things that I have done before, I can make a pretty good estimate. For example, I've learned that it takes me about 20 minutes to draft one of these blog posts. It takes another 15 to edit and re-write it. Then it takes me about 10 minutes to proofread, load it to the website, and schedule the post.
When I first started, I didn't know that, so I made the best estimate I could and then adjusted it as I gained experience.
The reason this was so revolutionary is that it let me schedule my day better. When I started to add up the time estimates for tasks and then look at my meeting schedule, I could see how my day would really look. Not surprisingly, I found that on many days, I would have 4 hours of meetings and then another 6 hours of tasks. So I either had to commit to a 10-hour day or make adjustments.
If I found a task that was going to take me 2 hours (like preparing to teach a class), I made sure I was going to have 2 hours to do it. If I wasn't, I planned how to break it up or I moved some meetings.
Another huge benefit was that I started to be able to handle the unexpected much better. For example, if I knew that I had 3 hours of meetings and 5 hours of tasks, but something unexpected came up, I could make better decisions on how to prioritize.
Try this for a few days - you'll feel more control over your schedule and will find that you get more done.