Before you structure a strategy, you need to know where you're starting out, and you find this out best by taking a GMAC diagnostic.
Typically students identify weaknesses, and these lie in content deficiencies, bad or compromised test taking strategy and negative mindset (which manifests through anxiety, lack of focus, low esteem, arrogance, low confidence, etc..).
Once you target what you need to do to improve your score, you can make an action plan that is either generic and 'one-size-fits-all' or customized to your needs sets.
There are benefits to the many different ways of approaching score improvement, and you need to consider which way(s) will be ideal for you.
Those of us in the field are here to help you along the way!
I look forward to hearing about your next steps.