Just reading study guides and doing practice tests I bought off Taobao. The 6 months leading up I almost exclusively did Chinese classes (level around HSK5) and the 6 weeks leading up to the exam studied HSK couple of hours a day. I was a university student then and had a lot of spare time.

A nice trick I learnt is, don't spend too much time on the grammar section (if they still have it). It is incredibly hard and you will struggle to find native speakers that can explain the concepts to you. Instead randomly select answers and use the saved time on other parts.