which board? if its AQA buy the lonsdale revision guides, they will cover everything you need to know. Practice questions does help but for GCSE you can get away with just memorise the equations, thats all you really need to do!
I hate them - they're so patronising. To the OP - make sure you know the basics backwards e.g. f=ma, v=ir, direction of forces, what each type of radiation is made up of etc. then just practice a ton of questions.
All I did for Physics was tons and tons of past papers from the AQA website after I made sure that I'd learnt all the formulas, and I got a high A, up from a D in the mocks. (Separate science, not double)
Know your formulae(formulas, whatever) and the few terms you have to know and practice, a lot. The past papers are your best friend, as rainbow drops said.
i hate physics. end of. but i find doin loads practise past paper r the best thing seriously !! n jst decide which r ur worst topic areas n concentrate on them !