To start off, I don't claim to be particularly good at essay writing, so this is not a guide on how to write a good essay. However, after a year and a half of writing essays for university, I have found what I think is the most efficient way to write an essay. At least for myself. So I've decided to summarize the flow here:)
This is written specifically about academic essays that I've encountered in university, the ones where you need all the proper citations. This post might not be too helpful if you are writing another type of essay.
Step 1: Brainstorm
Read the question: I like to start by breaking down the question. I try to identify the keywords and figure out what the lecturer is looking for. This gives me a good direction as a general starting point.
Find inspiration: This can come in a variety of ways. Sometimes I just stare at the wall and rack my brain. Sometimes I go on google, type in random related words and see what I can find. Sometimes inspiration comes unexpectedly. (The two essays I am writing this term are both inspired by random YouTube video recommendations.) This is why it's good to quickly skim the question as soon as you receive it, so that you have it in the back of your mind and it gives you a certain level of sensitivity to topics that may be relevant.
Mind-map: The next step is to decide on a topic. I pretty much just write down all of the ideas I have on to a page. And it usually is not as organized as a proper mind-map, just an array of random words on a page. But in this process, I get to think about the different dimensions of the topic that I can explore.
Decide on topic: I then like to condense the topic into one line. It's a lot easier to work with than a general theme. Keep in mind that later on, you would want every paragraph to link back to this topic, and you would want to have an answer or a resolution by the end of the essay.
Step 2: Read
Research: I then type in the random keywords from my mind-map on to Google Scholar and see what kind of rabbit-holes that leads me down. Usually one paper leads to the next and I just download them all on to a file. Sometimes I find it helpful to just read the titles and download the ones I find relevant, and then read the papers all at once.
Read: I mostly read the papers as PDFs on my laptop, and I make sure to highlight or underline quotes or key concepts that I think would be useful.