Whenever possible, look for peer-reviewed empirical research. These are articles or books written by experts in your field of interest, whose work has been read and vouched for by other experts in the same field. These can be found in scientific journals or via an online search.
Your thesis should express the main idea of your paper without listing all of your reasons or outline your entire paper. It should be a simple statement, rather than a list of support; that’s what the rest of your paper is for!
Use clear segues into adjacent points in your paper. Your essay should flow well, rather than stopping and starting in a blunt fashion. Make sure that each of your body paragraphs flows nicely into the one after it.
Annotating your research can take quite a bit of time, but needs to be taken one step further in order to add a bit more clarity for the outlining process. Organize your notes by collecting all of your highlighted phrases and ideas into categories based on topic. For example, if you are writing a paper analyzing a famous work of literature, you could organize your research into a list of notes on the characters, a list of references to certain points in the plot, a list of symbols the author presents, et cetera.