In his book Getting Things Done, David Allen talks about how your calendar is a list just like your to-do list: it's a list of time- and day-specific actions. It needs to be an accurate reflection of what you are committed to doing. There shouldn't be things in your head that aren't on your calendar, and there shouldn't be things on your calendar that you aren't really going to do. If you're finding that you are constantly late to things or are not getting your most important work done, it might be time to make over your calendar.
General principles for effective calendar management:
Keep as few calendars as you can get away with, and have guiding principles regarding what goes on which calendar. For example, having separate work and personal calendars might mean that you forget a weekday dentist appointment because it's not on the work calendar that you reference on weekdays, so a guiding principle could be that anything that occurs during work hours gets put on the work calendar.
Include pre- and post- appointment time when blocking your calendar for events. If you will need 15 minutes to gather your thoughts before an important 10 AM client call, book "Prep time" from 9:45 to 10 so that you don't find yourself in a 9 to 10 AM meeting that day. If you often have a lot of action items from your weekly directors meeting, book 15-30 minutes after the meeting for processing.
Block out time to get to/from your meetings and appointments. When you book a doctor appointment, go ahead and block out the time it will take you to get there and get back to the office. Tip: You may want to color-code "logistics time" differently so that you can tell what's a hard-and-fast start/end time and what's a little more flexible.
Time required: 30 to 60 minutes for initial cleanup, 10 to 15 minutes per week for maintenance
Set aside time to focus on this action item. A half-hour is probably enough, as long as it is uninterrupted.
Review your current calendar(s). Can you simplify/consolidate at all? If not, identify the guidelines you will use to determine what things go on which calendar, and try to avoid situations where you need to enter things in two different places.
Review your one-to-one meetings with your employees. Do you have at least 30 minutes scheduled with each person at least every two weeks? If not, figure out which days will be most reliable (least likely to have conflicts that require you to reschedule) and schedule them. If you do have meetings but frequently find that you're rescheduling or canceling them, figure out what will work better. Find an approach that you can stick with, and treat that time as sacred. Helping your employees move forward is the most important part of your job.
Add transit time for all of the appointments you have for the next four weeks. This includes things you have scheduled for evenings after work and any meetings that are in locations other than your regular office.
Add a recurring appointment for your own project work. A three-hour block is a good start; two three-hour blocks are even better. It is okay if this block has to be moved as the week evolves - it will probably rarely be on the same day week-to-week- but the key is that you have at least one chunk of time each week to work on the things you have to create, produce, and/or think deeply about in your work. If you're running from meeting to meeting, this work will never get done.
Block out the 15 minutes prior and after all of the meetings that are on your calendar for the next four weeks. (You can add a recurring appointment for this for any of your repeating meetings, far beyond the four weeks.) You can call this "buffer" or "prep" or whatever makes sense to you. The purpose is to ensure that you have time to breathe between meetings and aren't booked solid. This time allows for things to run over, for you to run to get more coffee, to process action items, or just stay on top of e-mail during a busy day.
Advanced: block out a meeting with yourself 12 weeks from now to revisit your calendar and other productivity systems and assess how things are working.
This post completely changed how I approached time management as a manager. It's obvious when spelled out: you cannot do deep work in 10-minute interstices between meetings. This post shows why you should batch your meetings (with buffer in between!) and your "deep work" time rather than taking a random approach.