Short answer: Read a section, close the module and write the key points in your own words, then keep only formulas, definitions and examples that you find hard to remember.
Why make notes from a module
Modules are long and meant for learning. Near the exam you need something you can revise in a short time. Notes made in your own words also help memory better than re-reading.
Before you start, check that you have finished the module chapter once. Notes written without understanding tend to copy the module line by line.
Step by step
Read one section, close the module, and write what you remember. Then open the module and fill in what you missed in a different colour. This shows you the real gaps.
Keep a page for each chapter. Write definitions, formulas, short steps for common methods and one or two examples that tested you.
What to leave out
Skip long derivations you already understand, repeated examples and details that are clearly outside your syllabus. If the module has questions, note only the ones you got wrong.
A good test is whether you could revise the chapter from your notes in about ten minutes. If not, trim further.
Keeping notes useful
Use headings and numbering so that you can find things quickly. Mark the three or four items per chapter that you keep forgetting; these are your priority for revision.
Review your notes at fixed intervals, such as after one day, one week and one month. Notes that you never open will not help, so keep them short enough that you will.
Quick checklist
Finish the chapter once, read a section, close the module, write from memory, fill the gaps, trim to key points and review on a schedule. That is the whole method.
If you share notes with friends, compare them. Different views of the same chapter can show you something you missed.
After you finish
When the exam is over, you may no longer need the module. Check the batch, year and condition before you pass it on, and see what to check in a JEE or NEET module.
You can list a module through sell books. Keep your own notes, since they are the part that is most useful to you.
If a module is badly organised, it is fine to reorder topics in your notes so that they follow your syllabus. Notes are for you, so shape them around the way you think. A clear order often makes a difficult chapter feel smaller.
Frequently asked questions
Should I make notes from every chapter?
Make notes for chapters that you find hard or that carry more weight. Easy chapters may need only a short list.
Is it better to type or write notes?
Choose what you will actually revise from. Many students find handwriting helps memory, but typed notes are easier to edit.
Can I sell my module after making notes?
Yes, if you no longer need it. Keep your notes, and check that the module is in good condition before listing.