Short answer: Pick a small set, schedule it against the syllabus and revise each book more than once.
Pick
Choose one primary source per subject.
Schedule
Divide chapters across weeks and leave revision time.
Revise and test
Test yourself after each chapter.
Frequently asked questions
Is one book enough?
For many subjects, one good book read well is enough.
When should I add a book?
Only when you find a clear gap.