The academic literature that you will deal with is often very complex. You are advised to take careful notes on each text that you read and, where you are stuck for time, to concentrate on reading fewer texts very well and properly understanding them, rather than skim-reading a larger range of material. In general, you should aim at reading at least one significant source on the topic of your interest and some additional literature, but it is much more important to understand a few texts well than to try to cover all the ground but thinly.
Plan your essay before writing it. Work out how your argument is going to develop before you commit yourself to it; the goal is to think everything through, then present a polished, finished argument, not to discover things along the way while writing.
Re-read the essay before you submit it. Look at each sentence and think ‘What is this contributing to the essay?’ If you don’t have an answer, delete it. For every substantive point that you make, think, ‘What is the foundation of this claim?’ If you are not providing any reasons to support it, it constitutes nothing more than an assertion or statement of faith and should be deleted. Think very carefully about whether you’ve proved what you are claiming to have proved. Editing and planning are really very important. Do make sure you allow time for them.
Proper footnoting makes your essay easier to read; properly attributed, it also enables you to hone your argument so that the extraneous bits are properly confined to the footnotes and enables you to situate your argument in the debates. It is a prerequisite for an undergraduate coursework essay and any postgraduate writing that you might one day hope to do, so it is a good idea to get into the habit now.
Often you will want to make a point that, while unrelated to the specific argument that you are making in the essay, is nonetheless interesting and pertinent. You should use a discursive footnote for this purpose. Discursive footnotes are sometimes discouraged by academic journals but are a useful device in essays at the high school and undergraduate levels because they help you remember what is, and what is not, relevant to your argument.
Sometimes you will want to directly quote authors or perhaps just paraphrase something that they have said.
Sometimes you aren’t directly referring to someone, but you are making a point that chimes with something that you have read elsewhere. You should note this because it helps show that you understand the debate to which you are contributing.