Agree with post #2
I found that whilst a lot of time spent doing further reading and just thinking about concepts, it is worth knowing how all physics grows like a fungus (sorry!) from core principles, the common habit of skim reading and pluggin in formulae, leads to A2 results that wont ever be excellent, and more importantly any decent physics degree application process will sniff out the memorisers!!
As an example in AS Physics I would make fully sure you understand how: potential difference, emf and electrical potential energy all form the basis of any electrical circuit. This crucial relation is glossed over in most AS books and by most teachers.