Personally, I've never been one for prepared essays or essay plans. Given how content focused economics is, provided you know your content, you shouldn't have too much difficulty in answering essay equations and thinking of what to write, often the essay question will tell you the exact areas you need to cover and you can structure your essays accordingly. What's really important is to know some stats unique to each topic to show more of your understanding of the given topic.
I am definitely not an expert or anything, but that's the approach that works well for me, it let me get a 19/20 in one of my trial essays, and 16/20 on the second cause I ran out of time and didn't cover one whole area (or three areas) of the question regarding unemployment, so in retrospect, it was pretty good bahahaha
Also, know your graphs! Having a clear understanding of your graphs, especially the higher-order, more complex graphs and knowing when to use it, or being sort of creative in a way, is an easy way to impress exam markers and tick those boxes. My economics teacher suggests including two for each essay if you want to get that 20/20.
Anyways, hope that helps!