Do not be afraid to start writing an essay. Take your time with the ideas that you want to imply in your piece of writing. Have your ideas first in your head without putting them down on the paper. When you feel like writing them down, take notes on every idea, word and phrase that comes to your head and relates to the topic of your essay.
You will need to keep a record of your sources so that you can include them in your bibliography. So when you find useful information which you might use, write down the name of the book or journal, the edition, page number, author, date of publication and publisher.