GCSE revision (for 2019)Watch
In the end I used a lot of youtubers (eg Mr Bruff, freesciencelessons, primrose kitten) and Seneca Learning. Did a bit of quizlet initially and then also really close to the exams but didn't actually find it mega useful. I also found that for humanities, flashcards and mind maps helped me a lot.
And I found revision guides really ineffective for me because I didn't pay much attention when going through them. I'm much better at doing engaged learning, which is why I like websites that test you.
But it's completely different for each person. So try from now / September try a few things and then when you find the one that works for you stick with it and do a little bit each day and at least an hour each weekend!