A manual for writers of research papers, theses, and dissertations, 7th edition - Kate L. Turabian 2007

Make subjects short and concrete
Revising sentences
Part I. Research and writing: from planning to production

Readers must grasp the subject of a sentence easily, but can't when the subject is long, complex, and abstract. Compare these two sentences (the whole subjects in each are italicized; the one-word simple subject is boldfaced):

4a. A school system's successful adoption of a new reading curriculum for its elementary schools depends on the demonstration in each school of the commitment of its principal and the cooperation of teachers in setting reasonable goals.

4b. A school system will successfully adopt a new reading curriculum for elementary schools only when each principal demonstrates that she is committed to it and teachers cooperate to set reasonable goals.

In (4a), the whole subject is fourteen words long, and its simple subject is an abstraction—adoption. In (4b), the clearer version, the whole subject of every verb is short, and each simple subject is relatively concrete: school system, each principal, she, teachers. Moreover, each of those subjects performs the action in its verb: system will adopt, principal demonstrates, she is committed, teachers cooperate.

The principle is this: readers tend to judge a sentence to be readable when the subject of its verb names the main character in a few concrete words, ideally a character that is also the “doer” of the action expressed by the verb that follows.

But there's a complication: you can often tell clear stories about abstract characters:

5. No skill is more valued in the professional world than problem solving. The ability to solve problems quickly requires us to frame situations in different ways and to find more than one solution. In fact, effective problem solving may define general intelligence.

Few readers have trouble with those abstract subjects, because they're short and familiar: no skill, the ability to solve problems quickly, and effective problem solving. What gives readers trouble is an abstract subject that is long and unfamiliar.

To fix sentences with long, abstract subjects, revise in three steps:

Identify the main character in the sentence.

Find its key action, and if it is buried in an abstract noun, make it a verb.

Make the main character the subject of that new verb.

For example, compare (6a) and (6b) (actions are boldfaced; verbs are capitalized):

6a. Without a means for analyzing interactions between social class and education in regard to the creation of more job opportunities, success in understanding economic mobility WILL REMAIN limited.

6b. Economists do not entirely UNDERSTAND economic mobility, because they cannot ANALYZE how social class and education INTERACT to CREATE more job opportunities.

In both sentences, the main character is economists, but in (6a), that character isn't the subject of any verb; in fact, it's not in the sentence at all: we must infer it from actions buried in nouns: analyzing and understanding (what economists do). We revise (6a) into (6b) by making the main characters, economists, social class, and education, subjects of the explicit verbs understand, analyze, interact, and create.

Readers want subjects to name the main characters in your story, ideally flesh-and-blood characters, and specific verbs to name their key actions.