Hey! I achieved an A* in Psychology so hopefully I can help with that..
I did Edexcel btw!!
So the most useful things I did were:
1) I went through all the questions in the exam papers and made sure I knew what the mark breakdowns were and how many essay question marks there were. I would make sure I knew how much AO1, AO2 and AO3 there were for each command word, whether that be Describe, Discuss, Explain etc.
2) I would do every single past paper I could get hand of. Some of the questions from the papers in 2009 were still relevant because of the mark scheme answers.
3) I would copy mark scheme answers into my notes because it is what the examiners are looking for!!! I would memorise these points.
4) I would look at examiner reports. These are SUPERRRR useful because the examiner is literally writing comments and giving you an insight on what they are expecting.
5) I would practice answers in timed conditions. Psychology was super difficult to finish because of the timing but I managed to finish because in my practice answers, I got used to cutting out waffle.
6) Lastly, make sure you go over the content as often as possible. Also try to give in practice essays to someone e.g. your teacher.
For general advice for all the A Levels, just keep trying to mirror exam conditions as much as possible. Do the past papers and do them again after a few months. Do ALL of them. Memorise the answers and make sure you know the command word for all your subjects. PLEASE look at examiner reports.
You got this
You can do it.