Make every second count.
Instead of browsing Twitter or Facebook before an class, try working on something more productive. I have a class that has practice quizzes online, so I do those before some of my larger classes where I have to come early to get a good seat. During a longer study session, take frequent breaks, even if it's just to grab a snack and don't be afraid to change subjects frequently. I like to get my homework done in really long study sessions, but I keep my energy high by fueling my body and changing topics frequently.
Make study guides.
Personally, I find the best time to review previous chapters is right before a test (that way I don't forget!) However, it can be time-consuming to review everything right before an exam. To cut back on the time you save studying in the future, make a study guide for each chapter you read to make it easier to review later.
Review before every quiz.
Depending on what resources your teacher/professor gives out, make sure you review as much as possible before quizzes. I review class powerpoint slides (if available), the textbook summaries and my personal notes right before a quiz to make sure I'm prepared.
Keep it organized.
A lot of people love using planners to keep track of homework. Personally, I use myhomeworkapp.com in conjunction with my university's website resources to stay on top of all my schoolwork. I also make my personal study goals "assignments" to be sure I get them done.
Use university resources.
A lot of universities have some form of tutoring center, often free, and sometimes individual departments or programs have their own as well. Even if your school doesn't have tutoring, chances are your professor is required to keep office hours and they can help you. Use any and all resources you're given: If you're able to rewatch lectures, rewatch them if necessary; If there are practice quizzes you can take, take them; If your textbook has a summary of each chapter, read it. Don't let laziness get in between you and an excellent grade.
Make it social.
Try to find study partners in each of your classes. Not only can they make studying more fun, they also have your back if you miss class and need notes. Additionally, there are often upperclassmen that can help you if you have questions about a course. Whether it's a TA or a roommate who's a year ahead of you in math, they'll probably be willing to help.
Leave your phone at home.
It's a drastic measure I certainly don't take every time, but I when I really need to focus, abandoning my phone for a couple hours really works.
Find your best times and to study.
I know for me personally, I absolutely do not focus right after class. So, I do all my studying in the morning before class, after dinner or on the weekend. Everybody's different and it takes a while to find your best time to study, but once you do, it's totally worth it. While there are tons of places to study on a college campus, depending on the time, certain ones will work better for you. I find it easiest to study most subjects on my own, so I study at home when my roommates aren't home (they all have fairly consistent schedules), in an old building's basement at night (it's not as creepy as it sounds!), and at the library on Saturday mornings.
Sometimes you need to tune out a loud roommate, and other times, music can just help you focus on your work. Find your favorite stations on Pandora, Songza or Spotify and bring headphones to whereever you're studying. As an added bonus, use noise canceling headphones like these ones.
Fuel your body.
Sometimes it helps to keep your mouth going while you study. However, you don't want to overeat. I'll portion out some almonds and vegetables to snack on while I'm studying, and chew gum the rest of the time. Drinking tea and water also helps me stay alert and focused.
The most important thing to remember when you're studying is that you need to find what works for you. Once you find a study routine that sticks, keep it up!