Whats the best way to learn with interest ? can you please give me some tips?

what should be daily intake food for to improve memory? what should i do when i dont have interest on learning on a particular day? can you please give me some tips to learn, since i have got a bad science teacher and i am in grade x so i need to study really well. sometimes i used to get ranks, when i just put a really small , nice efforts in which i start learning 1 month before the exam really nicely.sometimes i get really bad results even if i had put most of my hardwork on that. can you please help me out . thanks for geat cooperation.