As for tips I'd suggest revising little and often from near the start of the year. Doing this really takes a lot of pressure off of exam periods as constantly going over content ensures it gets stuck in your head! I found flash cards and past papers were key for biology, chemistry and psychology as within all of them there is a fair amount of memorization, more so in biology and psychology.
For Chemistry, a-levelchemistry.co.uk and chemguide.co.uk for websites. I enjoy E Rintoul, Allery Chemistry and Chris Clay are great revision channels. There’s not as much content in Chemistry but you need practice questions and, as with Biology and any other subject, keep on top of notes/flashcards.
Maths- PRACTICE. Make some notes on main methods, practice and refer to the mark scheme and notes. I’d recommed examsolutions as a website, which has all of their Youtube videos on as well as summaries. Jack Brown is another great channel, has a LOT of videos but they all target very specific methods.
I also do Psychology. I don’t really use videos for Psychology, I just make notes on the descriptions and evaluations of each of the theories/studies. Learning the structures for answering each type of question is equally as important, but they’re thankfully set (at least for Edexcel).
In general, keep up with notes, find practice questions, use your frees to study, use active recall to learn information rather than passively reading notes and don’t get wrapped up in any drama. Hope this helps