If you find one really awesome book or journal that fits your topic perfectly, try looking in the works cited/bibliography/reference list at the end of it. This should contain many more books and journals that are about your topic as well.
Although it is tempting to simply read over your essay and use the spell-check tool, editing your paper should be a bit more in-depth. Have at least one, but preferably two or more, person/people look over your essay. Have them edit for basic grammatical and spelling errors as well as the persuasiveness of your essay and the flow and form of your paper.
When you outline your main ideas, putting them in a specific order is important. Place your strongest points at the beginning and end of your essay, with more mediocre points placed in the middle or near the end of your essay.
Any information that doesn’t fit within the framework of your outline, and doesn’t directly support your thesis statement, no matter how interesting, doesn’t belong in your research paper. Keep your focus narrow and avoid the kitchen sink approach. (You know, the one where you throw in every bit of interesting research you uncovered, including the fungal growth in the U-joint of your kitchen sink?) Everything you learn may be fascinating, but not all of it is going to be relevant to your paper.