For school in general, live life so that you can be physically healthy and you will also become much more mentally healthy, thus being smarter and doing better in school. Eat lots of fruits and vegetables, exercise an hour a day, and get 9 hours of sleep. (For a teenager.) As for staying focused, try to turn what you are doing into some sort of game or competitive thing if you don't already enjoy it.
For example, in Spanish, which is rather boring, I count how many times I volunteer and try to volunteer to speak Spanish more than anyone else. I also try to be the first to respond when she asks how to say something. In math, I try to be the first one done, but I make sure it is quality work by checking with other students along the way. Some things I just like, such as band.
As for homework, just do it right away. I used to do homework right when I got home and when I stopped doing that I did worse in school. Starting right when you get home makes you the happiest throughout the total day. You may work a little slower, but the work will be of much better quality.
Breaks are overrated and are likely to drag out the homework project. If you are taking a break, make it short and sweet and make sure it doesn't involve electronics. If you get stuck doing a specific thing for homework or are reading the same thing over and over again without retaining it, switch to other homework or study something else so that your thought doesn't get muddled, but don't just stop doing homework.
Studying is tricky because everyone does it so differently. Just pull out some notes or a textbook and try some different technics. You can walk about while studying, as this will activate both halves of your brain. Don't get too comfy or you will get sleepy and think slower. Don't study at night, because you have already seen a lot that day and will have bad retention. Music helps a lot for some people and ruins study for others.
On the note with sleep, make sure you get enough sleep at all costs. It's almost as important as a good diet. Sleep is a time when the brain is not activated in real life and survival and is therefore a great time (and only time) to solidify information. It sorts through what has happened recently, but mostly that day, to figure out what is important. If something is especially pressing and is a recurring theme in your thoughts, you are likely to dream about it. That is why we have all dreamed about MCSG, we play it so much. Sleep is key in thought processes and problem solving. It gives us creativity and the ability to do things exactly the way we want to do them. Sleep is most effective when if corresponds with the natural human sleep cycle, in which we fall asleep around 8 or 9 and wake up around 6 or 7. Notice that that is about 10 hours of sleep. It seems like a lot, but you will feel best and get the most out of your day with around 10 hours of sleep. Those who like to stay up till 2 A.M. and wake up at 12 may think they are getting lots of sleep, but the sleep is less valuable if our bodies can sense that it is the wrong time to be sleeping due to light and timing.
Long story short, to do well in school, treat yourself well and make smart decisions in time management. Also, have a good attitude. Having a good attitude will make you do better at everything. I don't follow all the tips above, but if I did, I bet I could have a 99% grade average, instead of the 97% I get right now.
