For psychology I'd recomend starting with terminology and what the main perspectives are such as; behaviourism, cognative psychology, biopsychology, psychodynmanamic etc etc. Each topic will have core research/researcher's within them too (Frued, Skinner, Pavlov, Vygotsky, Maslow, Bowlby to name a few). For A level you want to be able to argue from every perspecsptive of psycgology raitonaly and with research and theory to support it. If you're looking to get a head start I will happily recomend some stuff