Short answer: Pick the books you already own, divide the syllabus into weekly pieces, and revise in a fixed pattern of reading, recall and practice. Buy something new only when you find a real gap.
List what you already have
Start by writing down every book, module and set of notes you own for the subject. Next to each, write what it is good for: concepts, practice questions or past papers. This often shows that you already have more than you need.
If two books cover the same topic in the same way, pick one for revision and put the other aside. Revising from many books for the same chapter slows you down.
Split the syllabus by week
Count the weeks you have left and divide the syllabus into pieces that fit. Keep the last week free for a full-length review. Be modest in the first plan; it is easier to add more than to recover from a plan that was too heavy.
Give harder chapters more than one slot. A chapter that you find difficult should appear twice in the plan, at least a few days apart.
Use a repeating pattern
A simple pattern works well: read the chapter summary, close the book and write what you remember, then solve a small set of questions. Check your answers and mark the topics you got wrong.
On the last day of each week, return to those marked topics. This keeps revision focused on weak points instead of re-reading what you already know.
Common problems and fixes
One common problem is a plan that is too ambitious. If you miss two days in a row, shrink the plan instead of giving up. Another is spending too long on a favourite subject while avoiding a weak one.
To fix this, put the weak subject early in the day when your mind is fresh. Also keep one short slot each week for questions you have been avoiding. Small, regular effort on weak topics is more useful than a rare long session.
Buy only for real gaps
If your plan shows a topic with no practice questions or a chapter where your book is unclear, that is a real gap. Then look for one targeted book, new or used, rather than a full set. You can browse second hand books or new books for that one title.
When the exam is over, books you no longer need can be passed on or listed through sell books. For making your own short summaries, see how to make chapter notes instead of buying more books.
Frequently asked questions
How many books should I use for revision?
One main book per subject plus your own notes and past papers is enough for most students. Add more only to fill a gap.
What if I fall behind in the weekly plan?
Move the missed items into the next week and drop the least important topic. Do not try to double up on everything.
Is it okay to revise from notes only?
If your notes are complete and accurate, yes. Check them against your main book for any topic you are unsure about.