In my school, there were a lot of projects trying to tell pupils how to do successful learning. Some of them were useful in special settings, but most of them were just ignored by most students, like me.
One example is the record card based learning of vocabulary. I always hated learning vocabulary, because it is just plain memorizing, there is no understanding behind it. Additionally having to maintain a bunch of cards never really helped, actually, I found it even more annoying to learn them. At that time however, computer aided vocabulary trainers were not yet widespread, maybe a record card based learning strategy is more helpful with a computer.
Even worse was everything regarding social sciences, history for example. I would have been glad if it just had been about learning dates and names. But additionally, it was about reading and "understanding" the stupid opinions of posers and explaining one's opinion (or at least the opinion the teacher wants you to have) to them.
While I never really had problems in science, I saw several people having problems because they simply did not find any way of seeing how science works. In everyday life, there is no need for proper definitions or fireproof reasoning as it is when doing science. You are rolling around opinions of yourself and others, but you have no need to prove them in an empirical or logical way, and learning to do this would probably be better than knowing the periodic table by heart.
So, well, I have done school, and I know others who have. I know people who were quite good, and I know people who were quite bad. I guess this gives me at least some eligibility to write a blog post about successful learning. However, I can only give suggestions, everybody must find his own way - probably the first thing to know: If you have found your own learning strategy, then keep it, even though others tell you it is bad.
The main lack regarding most recommended learning strategies I have seen is that they address exactly one thing very well. Namely the fact that if you practice things often enough, you will remember them. I cannot remember any learning strategy not being focused on efficient memorizing of matter. They give a way of learning certain kinds of matter fast. But they miss one crucial point: The personal interest.
No matter how hard I try, it is hard to learn something I do not really want to know. For some people, getting good grades is enough motivation to be willing to know matter. And in my expierience, the people with a better average grade were usually the people who did not really have any deeper interest in the actual matter but getting good grades. Just to make that clear, I am talking about the better people, not about the best people. And I am not talking about "nerdy" pupils who do not have any hobbies except learning for school, I am only talking about their interests regarding school matter.
So before you even try to make your learning more "effective", ask yourself whether you really want to be good at the certain subject. Ask yourself, why do you learn for that subject. It can be hard to be honest to oneself, so take your time thinking about it.
Maybe you have a deeper interest for the subject - which does not mean that every of your grades needs to be perfect. I had a deeper interest in Mathematics, still, my grades were not always perfect. School can also underchallenge you, and you should never forget that every school subject can be separated in a lot more subjects, and even if you like one subject in general, there may be parts of it that you do not like (like stochastics for me).
Still, if you have a deeper interest, then you should be able to learn it quickly, and therefore you should do so. And you should not stop at the level of current school matter: If school is too slow for you in a certain subject, try to get further information on it - books for the next class for example, or even university books, if you are good enough. Almost every subject has its own competitions on which pupils can take part. Even if you are not good enough to win a prize, participate, just to show other people that you are interested!
If a teacher notices that you become good at something, depending on how much of an asshole he is, he either will support you - then you should take this support and be thankful - or he will try to get you away from doing this - then you should ignore it. Do not try to discuss with teachers, you can only lose, and if you lose, you will probably lose more than just a discussion. Life is hard and cannot be lived without some kickbacks, and if you cannot manage to achieve all your goals, do not expect teachers to be able to console you. Some teachers may be able to, but some will also be glad about your failures, especially when they tried to keep you away from something before. Expect this. Teachers are just human, in the end. The older you get, the thinner becomes the facade of wisdom they want their pupils to see. And you are a factor that creates additional work. Keep that in mind.
Now, let us assume you have such a subject, then if you do not suck completely at everything else, you will probably not be the best of all pupils, but your grades will be sufficient for most things you want. There is no need to become good at everything.
In case you do not have any subject of interest, but you still do not feel successful enough, you should wonder why you go to school at all. Make up your mind about what you want to achieve. If it requires finishing the school you go to, then you should be able to find at least something interesting, because that usually means that school should teach at least some skill that is needed. If you do not think so, then you are probably missing something about your plans.
If you do not have any plans at all, then it is still better to finish school, to have a broader range of possibilities later. Then you will just have to learn to ignore your boredness while learning. This is probably the hardest part, because the usual learning strategies cannot handle this situation, they all assume that you actually want to learn the matter rather than being forced to.
They usually tell you not to have things that may distract you from learning. But presumably you are familiar with the situation that even though you try to keep away distracting things, you will find everything distracting if you do not really want to learn. The solution is simple: Have something that distracts you while learning. Do something else while looking at the matter. This is quite the opposite of what almost every learning strategy will tell you, and in fact, you will not even learn half as much as you could when just concentrating on the matter. So if you can manage to concentrate on it try to do it, but since concentrating on the matter is not always possible, having something distracting is basically the best possibility to find a balance between your boredness and your duty. Your grades will probably not be the best, but they should always be sufficient.
Trying to enforce your interest on a topic will fail, you can try to find something interesting in a topic, but if you cannot find anything of interest, you just have to accept that. Man can do what he wants but he cannot want what he wants, as Schopenhauer said.
And - even more important - never rely on teachers to make something more interesting to you. Probably there are some teachers who are able to achieve this. But mostly, either the teacher is pretentious and therefore not willing to give you instructions on why his or her subject is interesting, and therefore might hate you from the day you have asked, or he is not even interested himself. I coached pupils while I was still at school, and I have marked tests of teacher trainees at the university - I can say that at least in Germany, the latter case definitely occurs. Very often.
You may have noticed that I gave a quite bad image of teachers. Teachers are, as I said, humans. Teachers are the persons who give instructions to you - some of them enjoy their job, some of them hate their job. In any case, they are your instructors, not your friends.
You may like them on a personal level, as soon as you get old enough to have them let you know more about their personality. I have talked to teachers outside school, and some of them had quite interesting personalities. Of a few of them I even wondered how such a friendly person in real life can be such a dick during the lessons.
But that is how it is: They might be enjoyable in real life, but at school, which is clearly not real life, they are your instructors, not your friends. They have work to do, and you are part of the material they work with, and if you are difficult to handle, that is more work for them.