Don't leave it all to the last minute - This is something that I am definitely am never any good at. I am forever spending the last week before the assignment stuck in the library desperately trying to get it all done. (To be fair, I've never submitted a piece of work late. And I don't intend on letting this change any time soon....)
If you find you've already managed to ignore rule one. Then you have to get hardcore. It'll become a case of work, work, work, with the occasional break just to stop the stress, but by following these steps, I'd hope it'd get easier....
Keep Hydrated - Make sure that you drink while you work. Keep your brain hydrated and you'll find you can work for longer without losing concentration. (Besides, if you drink that much, the enevitable walk back and forward to the bathroom gives you a chance to get the blood flowing. Leading onto the next point...)
Get up and walk around when you find you're stuck - Get the blood flowing, clear your mind and hopefully when you go back something will give and it'll all be easier to work out.
Work with someone else that you know - Even if you aren't working together, the chance to sound ideas off each other or clarify something isn't such a bad idea. I find it so much easier. Plus you have the added bonus of having someone with you can be a great motivator...
Eat three proper meals a day - I sound like a parent, but your brain needs food and in all seriousness, how much work will you really get done if your stomach is protesting?!
Avoid Facebook/Twitter/your mobile/Blogs (delete as appropriate) - These only exist during assignment time to distract and waste time. Which you will probably need!
What do you guys think? What gets you through assignments? Comment below!