Working on the formulae is enough. You needn't go deep into derivations for Physics for NEET. You might need that for JEE Mains but for NEE Physics, learning the formluae and practising it will do. Memorise as many formulae as you can and write them down and stick them as post its so that you can always see them. Practise regularly and try various kinds of questions. Solving previous papers and mock tests to test your improvement. Keep a clock and check the time its taking you to solve these questions. And improve the time as you practise more. One day of the week should be set aside for revision so as to keep the mind fresh.