What should be the FIRST step when making an outline? Decide on the details to include as evidence in your outline.
Decide what information you will not include in your outline.
Decide what information to include in each paragraph of your report.
Decide on the main points to address in your outline.

Decide on the main point to address in your outline.

Explanation:

Usually when making an outline you would make your thesis statement first, however since thesis statement is not there the closest thing to a these statement is the main point to address in your outline.

Also when doing process of elimination anything that has to do with evidence comes second or when it comes to secondary info.

Hope that this helps