Estimate how much time you think it will take to do your assignment and double it. This may sound overkill, but padding your time could help you deal with obstacles like writer’s block, a dying printer, or other types of issues. Besides, if you finish early you can concentrate on going out and having a good time while the rest of your classmates are stressing.
Break your assignment down into small parts and set mini-deadlines for yourself leading to the instructor's deadline. Getting all the little pieces done will help you complete the final version on time and help you avoid stressing out as the instructor's deadline approaches. This might sound kinda dorky, but it'll work. Check out the Research Project Calculator which does just that!
Look over all your syllabi at the beginning of the quarter and stick due dates for assignments in your calendar or mobile device. Don't let deadlines surprise you.
Attend a time management workshop or other workshop for more tips and practical ideas.