At some point in the last ten years , I was a serious student. As was many of my friends, some of which now have Dr. in front of their name. The tips I give may not be necessary for you, as not everyone has to do really, really serious studying. But, should you or someone else on this forum have to do it....
1) Find a distraction free environment or make one for studying.
You have already identified things that distract you... the internet... your friends.... so start there.
Don't study in groups, and when you are studying, move away from your computer. Move into a different part of your house/apartment, one that you don't particularly like or find interesting.
Even if it means spending a significant amount of time in commuting, a distraction free environment is absolutely critical to getting studying done. The idea is, you need to put yourself in a place so boring, that your only choice is to getting through your studying to get the heck out of there.
When I was in college, I did this by retreating to some of the worst places on campus. I spent countless hours in a poorly lit basement vending machine area (which was visited by almost nobody), a computer lab that was empty after 5PM, and library areas as far from the main pathways as possible.
2)Homework is not the same as studying. Homework isn't always about skill mastery, it's sometimes just a waste of time.You use study time to master skills or memorize things, not do the repetitious "busy work".
Homework is something that can be done in the presence of distractions. You can do a few math problems, do some basic research, or type a paper with the TV/internet on. If you really find it hard to finish your homework, then the best thing you can do is squeeze it in the small intervals of time you have between tasks. This will keep your mind fresh and you'll be far more likely to finish the whole assignment.
I typically did homework immediately before and after lunch, as well as between classes. Everyone has a "down" time in between work/school and evening meal - try to capitalize on this time. These small intervals are key because hey, you can't really do anything else in these short periods of time... it's not like you can watch an entire episode of TV or play a dozen missions in your current video game of choice in 20 minutes.
3) Cellphone off while studying, no exceptions. This is time for your own mental development, and nothing else. If your friends seriously don't like this policy, then this should be cause for pause. Choose your company wisely. Your future success can be directly affected by your friends.