It is going to be most helpful to you to find examples that you can use to guide your writing.  If you are writing a thesis or dissertation, then there should be plenty of examples of these on file at the school.  There may be departmental requirements or expectations, so it would be good to outline the headings for the manuscript first.

If you are writing for publication, then simply review a number of journal articles from the journal(s) that you are considering.  Also, each journal has its own set of author guidelines, which you should download and follow.  This will make your life easier.

Doing these tasks will give you a vision and a feel for how things ought to look.  You get absolutely no points for learning things the hard way in life!

Your immediate goal should be to put together a skeleton to guide your efforts moving forward.  Consider the skeleton of the manuscript to be the headings and sub-headings.  This is the logical organization of the manuscript rather than the content.