Since you're already decent, I won't bother about the simple stuff. The thing that defines people in short answer is people who get 5/5 vs. 4/5. To help achieve this, you have to give the marker no reason to deduct marks...
1.
Make sure you answer the question and make it obvious that you did so. This also implies that you what all of the verbs mean. For example, if the question is "Evaluate the impact of ...", make sure the marker knows what you're evaluation is. I prefer to state it straight out, then present evidence and then conclude but you can do it just at the end if you want.
2.
Be concise and to the point: Too many people waste time because they don't understand what the question/mark value is asking for, whilst also going around in circles and confusing the marker. If its a one mark question asking to define globalization, don't give a four line answer detailing its impact on the global economy. Likewise, for a five marker, you want to cover everything you know about that topic. Going off this, look at the marks for a hint as to what they want. I've seen 2 mark questions asking to define Gross World Product. Since this is 2 marks, it means they are looking for two pieces of info. A lot of people will write something along the lines of "Gross world product is the sum of the production of the global economy" forgetting to include the point about "over a given period of time". The fact that this was a 2 mark question instead of 1 mark should ring alarm bells.
3.
Structure your response in a logical fashion. If the question says to discuss the impact of globalization on the global economy, I would start with something like "Globalisation has led to dramatic increases in cross border flows which has increased integration between nations and eroded national boundaries. Then talk about the benefits of globalisation. Then transition to the negatives through a connective such as "globalisation has however also accelerated resource use etc.". A lot of people write about both positives and negatives simultaneously which, if it isn't done well, is very hard to follow. Make your answer clear and you'll get full marks.
4.
Use stats to demonstrate knowledge. For example, a past HSC question was something along the lines of "Evaluate the impact of policies in X nation to improve eco development". If you don't have stats such as changes in HDI, reduction in poverty or whatever, its hard to convincingly argue the benefits of a specific policy.
Hopefully that helps. If you want, you can post one of your solutions and we can have a look at it. Good luck
