A key aspect that you will need to consider in order to make changes is to decide what you want from studying. Think about why you want better grades. Is it because you want to have a career in a field that requires high grades leading into graduate education (e.g. medicine, law)? Is it simply because you want to be proud of the effort you have put in throughout your educational career? If it's the first, my advice would be to focus intensely on the big picture, essentially on your career goals. Think about why you want to do what you want to do, and how great it will be once you get there, the pride that you will feel in that achievement, and the rewards you will reap for all the energy you have expended in seeking that goal. It may sound stupid, but I started doing this myself at the start of this school year, and it has worked great in motivating me to ignore the sacrifices you have to make in order to do well in university. Read biographies and autobiographies of people in the field that you want to be in; doing this keeps the goal it in the forefront of your mind and will encourage you to keep pushing on.

Once you've managed to do this, and have a clear picture of why you want what you want, it will be much easier just to sit down at your desk or in the library and grind out some study - because you are doing for a bigger reason than simply just for good grades.

As far as specific study techniques go, if internet procrastination is your enemy, this app will be your friend. You can enter certain websites which you want to block, choose a time (up to 24 hours), and block yourself from those sites. It is impossible to get around, even if you shut your computer down, take parts out, etc. Another good counter to procrastination is to study in a public place, like a library. Sit with your back to people so that they can see what you are doing, and you will be more inclined to work hard, and there will be less distractions in public places than in your house/dorm.

Another tip is to be careful with who you study with. I used to do a lot of study with my friends, but whilst studying with them made it more enjoyable than studying alone, I actually got very little done. I've found the best way to study is by myself, but if you do want to get involved in study groups, don't choose friends, instead choose people who do well and who apply themselves. People whose knowledge or work ethic you can benefit from.

My last bit of advice may be slightly controversial, but don't study to know your subject in-depth. Study for the exam you will be sitting. Study to get the best mark you can, not necessarily the best understanding you can. Study past exams in depth - usually the same questions will reappear every year, just phrased slightly differently or with slightly different numbers (particularly in science courses). You can use this to your advantage and maximise your efficiency by skimming over background info and engrossing yourself only in things that you know are going to come around in your exam. It sounds so obvious but you might be surprised how many people don't do this kind of thing.