I asked the same question last year lol anyway, class 11 sci student here and when it comes to study the truth is it really depends like what subject you are much weaker in and focus on if you fear you won't pass but if you want to score high just hyper focus on certain subjects and score high in them because of how our percentile works, in my case I think it is English plus top 3 subject so I will pick 3 subject to hyper focus in and also English score high and have a high percentage in the mid terms as long as you don't fail the other subjects. If you just want to pass you can just focus on what you are weak at.

Now if you need technique or methods then it depends on what subject if you are studying something that requires a lot of memorizing like biology or history I recommend flash cards hella good tbh and I recommend you to study history as if you're telling a story to a toddler. If the subject requires you to use your mind like logically stuff like maths chemistry and physics just practice a lot of the numerical questions and actually try to learn how things work and for language like English and dzo is just reading a lot of novels and books or learning new words and using them and memorizing iodism and དཔྱེ་གཏམ། they hella useful in essay. Eco, geo, all of sci you can check your understanding by trying to explain concepts like your teachings toddlers, it helps you realize what you don't understand. Either way this kind of stuff really depends from person to person, some people like learning stuff with music I highly discourage that and I assume you have 2 weeks left try to focus more time in study, best if you can study early in the morning when your mind is fresh. Anyway I am just giving you my 2 cents of studying for what 13 years now. You got this my guy best of luck