We all have many things to do, and we never have time and energy to do them all. We don't have time and resources to do them equally well either. Many things will be left undone, no matter how hard you try. Prioritizing is a way to solve that frustrating problem.

One key reason why prioritizing works, and works well, is the 80/20 Rule. The 80/20 Rule states that 80 percent of our typical activities contribute less than 20 percent to the value of our work. So, if you do only the most important 20 percent of your tasks you still get most of the value. Then, if you focus most of your efforts on those top value activities, you achieve much more than before, or you will have more time to spend with your family.

Prioritizing is about making choices of what to do and what not to do. To prioritize effectively you need to be able to recognize what is important, as well as to see the difference between urgent and important.
The important, or high priority, tasks are the tasks that help us achieve our long-term goals or can have other meaningful and significant long-term consequences.

At first glance, many of the tasks we face during a day seem equally urgent and important. Yet, if you take a closer look, you will see that many of the urgent activities we are involved are not really important in the long run. At the same time, things that are most important for us, like improving ourselves and our skills, getting a better education, spending time with family, often are not urgent.

With good prioritizing skills, you finish as soon as possible all the important urgent tasks, the ones that would get you into a crisis or trouble otherwise. Then, you focus your attention and try to give more and more time to those most important, but not urgent tasks, the ones that are most rewarding in the long run.
Prioritizing principles can be applied to both planned and unplanned activities.

For planned activities, like the ones included in your to do list, you can mark each of your tasks with "A", "B", or "C", depending on its importance. The "B" tasks should be done only after you are finished with all the most important "A" tasks, the ones that just must be done. If you have time after you are finished with the "B" tasks, you can move on to the "C" ones.

When you set priorities in to do lists, also keep asking yourself if any of your tasks can be eliminated or delegated.

When you prioritize unplanned activities, you often need to make quick decisions, and you don't have time to analyze the situation in full. It is best just to keep in mind your goals and rely on your instincts. Your effectiveness in such situations depends very much on the clarity of your goals.