As in keeping everything under control without getting overly stressed or tired.
What kinda school? As someone who spent a lot of time in college (US and Canada) here's the advice I would give.
Self discipline. Don't allow yourself to freak out over due dates or exams. Get into the habit of thinking of assignments, studying, and due dates in the way that the quicker you get everything done, the sooner your stress is alleviated. This way, procrastinating becomes less of an attractive option for you because you know it won't lessen your stress about your work. It's all in the state of mind - if you're frustrated and stressing out, you're going to have a hard time retaining anything you study, and that will just make you more frustrated.
On that note, don't cram everything at once, either. Some people can do this, but many (like myself) find this has terrible outcomes. The human brain has a hard time with this. If you've ever crammed your studying the night before an exam you may be familiar. Instead, study for 20 minutes or so, and take take a quick break. Do something you enjoy or that is relaxing and then get back to your work within a half hour. Keep doing this and you'll find you retain the information much easier and it's also a good way of managing hobbies and course work.
Take notes in a way you'll remember - don't struggle to write everything down word for word (that's why you have a text book). Specify in your notes of areas you really need work on and never be afraid to ask questions in class or lectures when appropriate. Don't be intimidated by teachers - they're there to teach you the material so make the most of them. You'll find teachers are often more than happy to arrange a time to meet or even group study sessions and there are often tutoring options available which are extremely helpful.
Lastly, keep everything organized, maintain friendships. Spend a few extra bucks on labeling tape or sorted binders and keep everything distinctly sorted and organized so you know where everything is. If you feel organized it's one less thing to stress about. Friendships are healthy and being busy with school doesn't mean you can't have them. Too many kids lock themselves in their rooms/dorms and lose their minds over school/uni which isn't healthy.
Relax, and take everything in strides. Organize, plan, and develop a routine that works for you. No answer fits all. Good luck.