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.

I think you should get a rough draft written as soon as you possibly can do so.  In many ways, this is the hardest part of the process.  The way to move on this is in chunks:

• Write the Introduction, Background, Methods, and References sections   first, and add to them and edit them as you go along.  These   sections are not going to change too much.

• Write the Abstract last, obviously, after you have written the   Results and Discussion sections.  However, you can write the   skeleton part of the Abstract since it usually has a little bit of   introductory text and background.

• Plan on using the Statistical Analysis Plan layout to organize the   Results section of your manuscript.

• Plan on writing the Discussion section in parallel to the Results.

Note:   Until you have the Rough Draft done, I recommend not showing it to anyone on your committe including your advisor!

The reason for this is that you will simply get sidetracked by your committee members brainstorming, knee-jerk criticism, and helpful ideas.  It is all too easy to get caught up in an endless cycle of changing the statistical analyses and results in order to try to hit illusory targets.