Everyone has their own revision methods that suit them best, personally I find making flash cards and mind maps a complete waste of time for me, but yes, past papers are probably the most essential and effective form of revision. Not only do you test your knowledge of the subject, but you get used to the format of the examination and you get a sense of the recurring question types so you know exactly what to write when they come up. By looking at the mark schemes afterwards, you see the way in which the examiners want you to structure your answers, which keywords will gain you marks and which parts of answers are unnecessary.
However, it is important to revise in other ways as well, as it's likely that the available past papers don't cover the whole specification. I found copy/pasting the specification into a word file and then making notes under each section quite useful, that way I knew I hadn't missed anything. A handy tip I wish I'd found sooner is to check out the examiner's reports after you've sat and marked a past paper. You pick up all sorts of useful tidbits, and the author of the report will highlight general trends of areas candidates tend to be weaker on, and provide an insight into the way exam papers are marked and what the examiners are looking for.