Identify your top priorities. All jobs aren't equally important, no matter how urgent they may appear. Due date alone is not always an indication of priority.
Make a list. Putting all your jobs and their deadlines into chart form helps you weigh one against another when setting priorities.
Know how much you have to do on each job. With certain jobs, raw information produced on time is more important than a fancy finished product. Instead of handling a multi-part project all at once, can you handle it over several days?
Drop everything but the important. Switch your phone to voicemail. Put a "Do Not Disturb" sign on your door. A few hours of concentrated effort can produce great work.
Weed your garden. Can you cancel anything? Can you delegate to someone else? Eliminating items can give you considerably more time.
Spend a little time on a lot of projects. Try breaking your work into segments. Devote a set amount of time to each important project every day.