If you are struggling to understand one particular concept then ask your instructor to go through it with you. I did that for elements of Met and aircraft technical and it helped a lot.
The exams may seem boring, especially if you're at school and the last thing you want to be doing whist away from AS levels is "more school" - I do know that feeling. However you do need to know the material well even after you've passed the exams and obtained the ultimate objective - you're PPL. Since I've got my PPL I've dipped in and out of the Air Law and Met books to brush up on certain elements that had been pushed to the back of my brain (icing for winter flying for example). I'm still re-reading the technical book as that's the exam I had most trouble with and it's stuff that I need to know with confidence.
In short, whatever approach to ground study you choose, be ENTUSIASTIC! Try to get as stuck in as possible, you need to be determined to get that PPL.