A paragraph consists of at least six sentences and at most 200 words that say one thing and support, elaborate or defend it.
The key sentence says that “one thing”. It is one among several (usually around 40) things your paper says. Each paragraph should make a claim that is proportionate to the others,
as the hand should be proportionate to the head in a drawing. Also, a balanced drawing renders each part of the figure with the same amount of detail. Don’t write a tight, rigorous theory section and a breezy analysis.
My theory of the social world conditions the way I see it for analytical purposes. My theory helps me to see certain things and prevents other things, not relevant, from distracting me.
In your theory section you tell your reader what you are able to see and what you are unable to see. In your analysis you tell your reader what you actually saw in your data.
Keep your writing back. Don’t finish your theory section before you have written your analysis. Let the whole paper emerge gradually.
Don’t stick your “limitations” on at the end. Let them emerge in your methods section as determined by your theory, and let them guide the presentation of your data, collected according to your limited methods. Let the analysis run into its limits squarely as you proceed. Don’t instill a false sense of generality in your reader’s mind and then retract it at the end.
Think of the key sentences as the bones in the skeleton of the figure. Remove the prose around them and you expose this structure. It is okay that the bones are not “touching” in the outline; cartilage and muscle are presumed to keep them in the right relative position in the actual paper. The important thing is that the toe bone be connected to the foot bone, the foot bone connected to the heel bone. Etc.
The introduction is connected to the background, the background connected to the theory, the theory connected to the method, the method connected to analysis, th’analysis connected to d’iscussion, and now hear the author out (that’s the conclusion, of course.)
You write the paragraphs to “flesh it out”. You keep the key sentences short and simple. They simply state your claims.