Hi, again, Cambridge IELTS books are the only one I have ever practiced on, for both Academic and General Training tests. A month before the test, I often finished at least 1 book per week for Listening and Reading sections.
From personal experience, to get 9 on Reading, you should stop after the 2nd books (after 8 mock tests), studying on what type of task you're losing point most often. It's always T/F/NG type for me, so besides continuing with full mock test, I tried to find more test examples of that type and practice more on it. I went back to older Cambridge books and just practice on that type only. I took IELTS GT twice, got 8.5 and 9 for Reading. Another note to keep in mind, for Canadian Immigration purpose, 8.0 on Reading is already the maximum requirement for CLB 10, I myself didn't sweat on the 9.0 Reading.
Then for Listening, honestly, there's no tips and tricks for me on this section, other than listening to English everyday and improve your listening skill naturally. Practicing on Cambridge books might help on the types of task (like preparing to note down phone numbers, strange street name with the help of spelling etc.), but if your listening skill is not that good, you'd easily get lost on Section 3 and 4 of long conversation and long monologue, and you can only guess the answers. I personally left Ted talk video running as background noise while I'm working, to kinda passively listen to it. Same note with Reading, find out what type of task you're weak at, get more practice on it. I'm always scared of matching places on the map, while my friend often lost points on dictation.
