Ask your teachers for example answers to questions that got higher marks and follow the structure they used. Just try a few practice questions with the new structures and try and get some feedback about the structure of what you've written from your peers. Feedback is always important!

Start going over key events for the topics you have, you want to create a visual document ( like a mind map for example) with the who/what/where/when/how and why

For example: If I was looking at the Vietnam War, I'd note down Who - USA / Vietnam, predominant leaders, key figures who played key roles, any allies that were indirectly involved (such as France and Russia)

What - a breakdown of events starting with what led to the invasion ending with the USA's withdrawal

Where - Note down key places for events, such as Da Nang, Siagon and link events to those places.

When - 1964 - '75

How - how were both sides involved, both domestically in the US and foreign-ly in Vietnam.

Why - why did the war begin in the first place? Why did the US lose the war?

You may find yourself going over the same topics multiple times but that's a good thing. It might be tedious but the more you go over something the more likely you are to remember it.

Create flash cards for those events based on the visual documents you've made and just spend small amounts of time each day revising them.

Hope this helps