Here are some of the points I found to be most important. The first one being keeping in mind the purpose of the paper. This is huge for me as I often do not stick to one theme throughout the paper.
The second is discovering who the audience is and how to write to them. Doing this keeps you from writing papers not suited for a certain audience.
Finally the third point is planning how to write the paper, not necessarily writing an outline but more getting your thoughts organized. This is very helpful when coming up with a thesis.