i got A* in a level edexcel psychology a few years back, the main tips i’d share is to understand question structure (knowing what the question word means, when to use ao1, ao2, ao3 and how many points to include - mark schemes generally include info on this), and when you get closer to mocks try and make your own model answers for potential essay questions (like questions asking to evaluate or discuss theories)
in terms of resources the specification should set out what you’re expected to learn so you can keep on track, and physics and maths tutor has plenty of resources like notes and past paper questions to help you understand content and have some practice. i’d recommend you take a gradual pace if you’ve just begun studying a level psychology since it is content heavy and its more important to understand theories/studies before starting exam practice