This tip’s focus is on passive voice. Passive voice is formed with the verb to be and a past participle: is known, was found etc. Passive voice obscures the actor and causes the writer to back into the sentence, e.g., This finding is supported by the authors; as opposed to active voice: The authors support this finding. Or the actor can be left out altogether: This finding was supported.
There are three problems with the passive voice: it adds words; when it doesn’t it hides the actor altogether; and third, it makes it harder for readers to process the information because the logical word order is reversed.
The advantage to the active voice is that it saves words, identifies the actor, and uses the normal actor-verb-object sentence order.
There are times when passive is good. These are usually in the method and result sections of a paper when the actor is obvious and the thing being acted on is the focus, i.e., a result or a method.
Many journals frown on the use of passive voice because it lacks clarity. So, if you want your writing to be clear, stick to active voice as much as possible. And hire a good editor.
The topic for this tip is repetition. I find that academic authors view this issue incorrectly. Often it seems they view repetition as using the same word more than once, e.g., using firm, company, and business. Your writing is stronger when you stick with one term; consistency in terms is valuable.
Another form of repetition is the use of a noun as a modifier: The high firm performance allows firms to garner higher profits. I see this type of construction a lot. English gives you ways to avoid this issue, e.g., Higher performance leads to better profits for firms.
The real repetition is of ideas or statements. This type often occurs because lecture notes are the basis for the paper. When writing for a journal, your audience changes. Now you are making an argument not hammering home a concept; you are writing for peers, not students.
So, think about consistency and strong statements made once.