While you are planning your essay and while you are writing it, you need to decide how much use to make of the notes you have made from your reading. Whatever technique you develop, I strongly recommend that at some point (probably when you make your plan) you put all your books and notes aside (put them in a cupboard or a drawer completely out of sight), think about the title and the central argument in your essay, and then on a clean sheet of paper work out a the basic structure of the essay.
You might want to go even further and write the first draft of your essay with your notes still locked away out of sight. This may sound daunting, but it is actually surprisingly easy – especially if you have been through the processes of active reading, thinking, talking-through, and planning suggested above. You just need to write a succinct paragraph or two to explain what each point on your plan means. When you have done this you will find that you have written a first draft of your essay. This technique has enormous benefits in terms of producing a lucid, readable and argument-driven piece of work rather than something that resembles a shopping list or a mish-mash of unconnected thoughts and quotations. Another great advantage of writing a first draft in this way is that you will inevitably produce your own paraphrase of other people's arguments rather than falling prey to the temptation to copy out quotations or use the author's own words in a barely changed version.
Another useful technique you could employ at this stage in the planning/writing process is – once you have worked our what your argument is going to be – to start off by writing the conclusion to the essay. This is a good way to focus your mind on what the rest of the essay is working towards.
However far you get with your books and notes locked away you will, at some stage before producing the final version of your essay, need to consult them again; at this stage you can pick out particularly useful quotations and examples with which to illustrate your arguments. You can also make sure at this stage that there are not any crucial things in your notes that you have forgotten about, and that you have represented other people's views fairly and accurately.