Important books for reading, one called improve your reading skills and another one called official ielts Cambridge. These 2 books teach you how to answer reading properly. I advise you to practise 3 reading together with timing less than 60 min. Secondly, the best effective strategy in reading is to read first 2 questions and highlight the key wards like names with capital letters, date, occasion and then search for them in the first and second paragraph by skimming and scanning strategies and so on.
To be honest I have practised what is called advance English books which have very very hard readings which helped me to find IELTS reading easy. I believe that official ielts book of Cambridge is the best book ever, even the tests inside this book is really hard which is more difficult than IELTS examination itself. For beginners, don’t be sad if you get 5 only during your practice, keep practising with timing, and after you finish check why I got these wrong answers. The best thing to improve your IELTS score is the reading, read as much as you can without translation this is called extensive reading. This will not only improve your reading, but also will enhance your writing and speaking. Read anything you like, magazines, newspaper, novels anything you are interested with. I used to read all the articles that I practice after I finish them. Best magazine in my opinion is new scientist and the economist, and best newspaper in my opinion is Independent and the Guardian. Finally, the most crucial thing to do is to stop studying anything 3-7 days before your examination. Sleep 10 PM last three day before your examination, cofeeeee on the day of the examination. Don’t touch any book in your examination day. Unfortunately, the overwhelming majority of people who fail in the IELTS test is because of the stress of the examination, therefore, sport is very important during your study to improve your intellectual understanding and your overall performance. I would like to remind you that the percentage of British who perform IELTS test to get band 7 is only 40 %( you can check the ielts statistics by yourself) , so don’t be frustrated because you failed few times. IELTS is an accumulative issue, this means that how much you study how much you will improve, don’t give up.
Best luck 🙂 .