Physics (and Maths) are hierarchical subjects. Only when the lower levels are sound can you add on more levels of complexity.
The secret to success according to our founder and expert tutor Matthew, is to focus on the fundamentals. A good example is: instead of worrying about completing every question in every exercise in the textbook, cherry pick some of varying difficulty. Also attempting some of the proofs from scratch (obviously do look for inspiration if you get stuck!) really helps cement the fundamentals.
Look at older textbooks too, sometimes seeing the same concept (eg. charges in magnetic fields) presented in a different light, can make all the difference. Ask your teacher(s) what books they used or what other books they would at least recommend.
