I am a freshman, and I have never done homework at home, or studied for any test/quiz for that matter.
Its not that my high school is easy, it is just that I am good at maximizing effort at study halls, and finishing homework in-class.
I have a 3.5 GPA, but I figure that will drop A LOT if I continue to have this work ethic, but I am too lazy to actually work.
What can I do?
I’m in the same boat as you, except my realization came a bit too late. I’m a sophomore who ran through my algebra 2 class thinking i could just wing it and still be fine, it wasnt until i was just barely passing by the skin of my teeth at the end of the semester that I realized that I need to get my act together. Algebra 2 is passed and i barely got a 62 overall and i have no one else to blame but myself. I’ve been doing a lot of trial and error on what I like best when studying/doing work. For me listening to music while I work is the best. I also start with something small so i don’t overwhelm myself with work.
Really, as much as i hated getting this advice when I was asking for help with studying, you have to just suck it up and get the work done. However it most helps you and makes studying as painless as possible. It’s been a few weeks of me really trying, and there has been improvement in my work habits. Not very big, but i don’t wait until 10 o’clock to do (most) things. So just take some time, you can’t erase a bad habit in two days, sit down, plan out your long-term goals for your grades and do whatever it takes to make it happen.
I’m probably not the best person to answer this since I’m really good at procrastination…but you could try these tips:
[ul]
[] Use LeechBlock or another similar addon: block sites that you waste time on (I block this site, online gaming sites, and other forums during times that I allocate for homework and after I spend a certain amount of time on them (usually 30min)
[] Stay organized: keep a list of assignments that you need to complete and when they’re due. Try breaking it up into little (15min - 30min) chunks so you can check stuff off and feel good! 
[] Track what you spend time on: still something I’m trying to do–basically have a table with time slots of around 30min, and after each time slot, I mark what I did at that point. Since I don’t like to admit that I waste time, it helps me keep on track.
[] Sleep enough: when I don’t get enough sleep I find it really hard to be motivated, and I end up in a general “it doesn’t matter and I’ll do it later” mood. Plus it makes me feel bad in general…
[] Take breaks: I simply cannot focus for more than an hour for most heavy subjects, so I take breaks to eat, go outside, or do something more fun. Just make sure to put a cap on how long the breaks are!
[] Don’t think that you can put it off: putting stuff off makes it worse. Period. Try your best to get into a habit of finishing things one day early–I know it’s really hard, almost impossible, but once you get it, it helps immensely.
[] Don’t do it by yourself: work with friends on assignments, help each other check, or do something else so that someone is involved in your work before you submit it. I prefer to work with friends over my parents, but see what works for you.
[] Understand where you are wasting time: for me, this site is definitely one of the main culprits…and I’m still trying to find effective ways to not obsessively check it.
[li] Find subjects that you enjoy and that are challenging: I slack off, and therefore tend to do worse in, subjects that I think are easy. I know you probably don’t have much flexibility in your schedule, but next year, try to take more honors or AP classes in areas you like.[/li][/ul]
Good luck!