Took 4 GCSEs in Year 10, currently in Y11. Got A*AAC in maths, history, computing, and French, respectively.
For maths, I went through the CGP revision guide and made notes on what I struggled with and then done questions from the workbook and marked them. Also printed off a LOT of question papers and those papers on specific topics and went through those.
I did the most revision for history. Early in Y10 we had a mock coming up and my teacher asked us to create a small revision poster thing for Germany 1918-1945 for homework. I did it the night before and created a ~90 slide powerpoint full of information in 3 hours. From then, I didn't really need much revision for Germany. For medicine, I made small revision posters and highlighted the important facts and made it quite colourful, and I stuck those on my wall - you couldn't even see my wallpaper. I also found a PowerPoint that was a Germany timeline, and printed it out, so that there's three on each slide, and stuck that on my wall. I only did a couple past papers. I was 2 marks off an A*, forgot to get it remarked.
I didn't do a lot for computing, just some quick note taking the night before. For French, none, just went to the crammer lessons.
I will be doing the revision technique that I did for History for my Science this year as it seemed to work great!