I used to be really good at time management. I am struggling with it as of late. I'll discuss what worked back in the good old days.
Your first step should be to read 'The Seven Habits of Highly Effective People' by Stephen Covey.
Next you should sit down and write down goals for yourself. We often produce activity without achievement. If you know what you are trying to accomplish, then you can forgo actions that do not help you toward your goals.
Next try to schedule your week. Of course things will not happen as you hope they will. But make it a habit to sit down Sunday morning and sketch out the week ahead.
Next try to develop a to do list. I know these can become burdonesome. One trick is to create two lists. One list would be labeled your 'perhaps' list. This would consist of things you would like to do if you have the time. Then you would have a shorter 'to do' list of the things your really must do.
Next make it a habit of distiguishing what is important and what is urgent. Urgent items can seem important but often are not. How many times have you rushed to get something done only to find later that it did not need to be done at all?
Try to accomplish one Quadrant II activity every day. Quadrant II items are important but not urgent. This could be studying, self improvement, exercise or other beneficial tasks. These help your overall effectiveness. Unfortunately, because no one is yelling at us to get it done, we often fail to do these critical tasks.
Next try to understand your rhythms. We each have different activity levels through the day. Some of us are morning people while others are more effective at night. Try to handle complex matters when you are at your best. Assign more mundane activities to times when you are less alert.
Next divide your week. Avoid scheduling difficult projects on Monday mornings or Friday afternoons. Block out time to handle your difficult projects at a specific time, like Tuesday mornings, every week.
Use Voice Mail. Some tasks require uninterruped attention. Let your voice mail answer the phone. Once you have completed the project, call people back right away. They will understand. Often your phone will be busy simply because you have not been effective at getting those difficult items accomplished. Once you get caught up your phone might actually slow down.
Next, get some sleep. You'll get a lot more done if your brain is awake.
Finally, don't get bullied. We are often stressed out because someone dumped something on our laps at the last minute. Refuse to accept someone else's sense of priorities. A great saying is ' A Failure to Plan on Your Part, does NOT Constiture an Emergency on My Part.' Put that on your screen saver.