I would advise you to start with buying ACCA material from either BPP or Kaplan. They are both very good. BPP is a bit more wordy- helpful if you are new to accounting. Kaplan is more concise and to the point. Both books cover all the topics.
Start with the study manual, and make sure you understand the concepts. Then move onto the question banks/ revision kits. The most important thing with any ACCA exams is question practice. Complete each revision kit atleast once. And a second time would be ideal. Also, when you get any question wrong, come back to it later on and do it again till you get it right. Also time yourself while doing question practice.
Once you are comfortable with the revision kits, you are good to go for the exams.