Write down everything that comes to mind. If you do not have a topic predetermined then make a list of general topics -- such as literature -- and branch off into specific topics -- such as "War And Peace." If a topic is already provided, then brainstorm ideas for a direction to take the essay in. Decide what important factors are available for discussion within your set topic and expand upon them. For instance, if you are to write a research essay linking an author's life to his works, then consider the elemental themes that continually come up within his works.
Researching before writing is more than just a good idea -- it is fundamental to the writing process. Researching your topic is the basis for which you will construct the entirety of the paper, and lend your claims the credibility they need to be taken seriously in the academic and professional world. Use library resources to find credible references in text and online. For text, consult encyclopedias, journals and critique books. For online, use sites with domain names ending in .edu, .org or .gov instead of sites ending in .com -- unless the .com is from a well-known and credible source.
The thesis is the central focus of the essay that pulls the text together into an organized effort. Think of the essay as a planet and the thesis as the planet's gravity -- without it, the world would descend into chaos. The thesis is usually placed near the end of the introduction, but there is no concrete rule for where to introduce the thesis; so long as it comes naturally and before the main ideas of the essay, it is perfectly suited for placement anywhere. There is also no limit to how long the thesis should be, but it is generally about one to two sentences in undergraduate papers.
The outline is the blueprint of the entire essay, based solely on the effort you put into brainstorming, researching and formulating the thesis. These previous duties inform the outline by creating a structure for which the entire essay will follow, at least tentatively. Essays are outline with a series of main points followed by several sub-points to support the main one.