postsemgirl, Yes, we know how you feel. Here’s what I do that works:
1) Be realistic. Set aside two or three blocks of time which you can spare for doing the assignment. Then plan out that time (ex. 1/2 research, 1/2 write). This takes away most of the stress.
2) Once you’ve done that, whatever you do, you do and whatever you can’t, you can’t! Do your best and leave the rest up to Hakadosh Boruch Hu! This takes away the rest of the stress!