Pags ocr a chemistry alevel

Hi! I dont know if this is a stupid question but does anyone know for OCR A CHEMISTRY ALEVEL what we actually need to revise in terms of PAGS like methods/calculation? or if we need to even revise them at all? or if there are some we need to know or not?
I also saw ppl make videos on practicals that aren't even PAGS e.g. waters of crystallisation and just confused in terms of practicals what is important and not as someone just starting y12 chem
Any help would be great! I have an exam after half-term and just want to be efficient in revision