Hi, I'm doing IGCSE too.
I recommend Physicsandmathstutor.com for topical past papers and summary notes
This is what I do (for science):
• After I get back home, I would take my notes that I wrote in class and add more information to them using the syllabus as my guide.
- For topics that I'm confused on, I would ask my teachers for help.
• Once I've done a whole topic of notes, I use flashcards and condense the information into little pictures since that helps me remember information more. (see attachment)
• Once I'm finished with a topic and I know the topic by heart then I will make summary notes using the active recall method, where you try to "blurt" out all of the information you can remember about the topic, without using your notes, then cross-checking it with your flashcards and writing the information you've left out in a different coloured pen. (see attachment)
For maths, I basically just do past papers, and for the questions I don't understand, I would watch a video on it or ask a teacher.
(Sorry about the quality of the pictures by the way. I took them using my MacBook camera.)