Work smart not hard - don't kill yourself overworking. Just make sure you're on top of things as you go along (so then you won't have chaotic hell when it comes to exams), and when you do do work, focus on the areas you're less confident in. If you find what works for you in terms of revision, you can save a lot of time as well - don't waste time painstakingly writing out notes for revision, for example, if you work better making mindmaps or using Quizlet