Most people never master time management on a personal level -- what time to wake up, what chore to finish first, assignments are usually past deadline -- but the stakes aren't especially high in that venue. Time management at workplace, on the other hand, is a critically important skill to master.
Skip a few deadlines at work and you are likely to hear a word or two from your boss... probably even co-workers, as their work might depend on completion of yours. Hence, mastering time will ensure you finish all task in time, in fact you will even find time some time for yourself. Many times, we miss tasks that were discussed but were low priority at the time of discussion or were supposed to be executed sometime in future or just because nobody followed up on them. I am sharing some tips that have worked for me in task management.
Marking Emails Unread After Reading: If the email content requires you to take action like a link that has to be read or an attachment that needs your attention, or responding to an RSVP, mark the email as "Unread". Make it a habit to mark your calendar to review all unread emails once/twice a week when you are likely to be less occupied. Type "Label:Unread" in Gmail to pull out all the unread emails; you should be able to go through the queue and finish it off in less than an hour.
Mark Calendar for Anything and Everything: Use the calendar effectively by using it to plan your tasks. For instance, you need to prepare a document or write an email or research on an important client you will meet the following day - mark your calendar for a suitable slot. Even if you are not able to dedicate time to the event during the scheduled time in calendar, postpone it to another suitable slot. It will ensure that you do not forget about the same. It will also help to ensure that others don't disturb you unless it is something very important since your calendar shows you are busy.
Acknowledging Calendar Notifications: Google calendar supports two types of notifications, email & pop-up. The best way to use them is to have an email reminder 10 minutes before the event so that you can prepare yourself towards finishing the task. Initiate a pop-up one or two minutes before the event so that you can walk up to the meeting room, or find a number to dial or even pull up documents in time for the event. If something important pops up, again, you can always reschedule the item, keep it unread and review them later.
Acting on these tips will ensure that you are managing your time effectively by taking up more or cut down on responsibilities. I have used these tips myself and can assure that you will find more than 30% vacant time by implementing them.