For me, the best way to do it is to write all of my concepts on post-it notes and then lay them out in the order I would like to discuss them.
This takes the clutter out of my brain and allows me to work it around until it is organized.
Laying the post-its out on a white board is helpful since you can use your marker to add notes or arrows to help your essay flow.
Writing your first draft becomes effortless, just grab the first post-it and write. Then move on to the second one! Repeat until you get to the final one.
If you've got a word count target, this is also a great way to determine before you begin if you've got enough content to work with. If you can write 100 words about 10 ideas, you've got a 1000 word essay, and slightly more with an introductory and summarizing paragraph!