Always use a planner: as you probably all know by know, my planner obsession is completely out of hand!! I currently have three different planners for this year and I've been using them all SO much. I love writing everything down and truthfully when it comes to school, I have to or 90% of assignments would never get done! I love using fun stickers to decorate my planner and keep it organized too.
Color codes: go buy some fun colored highlighters and highlight EVERYTHING! Well maybe not everything but I think you see where I'm going with this! I highlight notes, important dates to remember; anything to help me stay organized and get things done.
Make list after list: when I get a syllabus for each class, I go into Microsoft Word and make a list of every single assignment for every class in order of the dates they're all due. I've found this to be extremely helpful (on top of all the planner organizing) because it really assures me that I'm not forgetting to do absolutely anything!
Take good notes: for some classes I take notes while for others I print out the PowerPoint slides (if it's possible). Depending on the class, I find that writing things down helps me learn and retain information but there's some classes that either have way too much writing to possibly grasp what's happening or it's a subject that I don't think I'll need the extra writing for. Either way, having really good and organized notes will help you to study when it comes time to. It's crazy to me whenever I see someone never writing anything down - I'll never understand!
Have an organized work space: if my desk is a mess, then my life likely is too (just kidding, sort of). Find cute storage and filing boxes to keep the semester's handouts in, keep a jar of extra pens handy, light a pretty candle and buy yourself a calendar to keep on your desk. Nothing keeps me more organized!