I used to set myself mini-deadlines when I was in school.
I'd figure out how many days from assignment to due date. Then I'd set aside a certain number of hours to get a certain amount of work done. Ex: find and check out or print out or photocopy relevant materials on the first night. Second night, scan materials and highlight good quotes to use. Second or third night, come up with some sort of thesis and outline. Fourth night, type up all quotes I intend to use. Fourth or fifth night, organize quotes. Fifth night, flesh it out a bit- just work on one paragraph or add a few sentences around each quote. Sixth night, flesh it out a bit more. Repeat until I have a paper. Finally a night or two to edit the work for grammar, punctuation, etc. If possible swap papers with someone else in the same boat after editing own work. Fresh eyes may see something I've missed, and an outside mind will not automatically complete familiar thoughts.
Having so little work to accomplish each night eased my anxiety substantially, and it was harder to put it off when I thought of it as only photocopying, or highlighting, or an outline, or a statement, or a paragraph, or editing.