Each tip could, and should, be explored in more detail, but this overview will hopefully serve as a good starting point.

1) Noun phrases

Noun phrases are useful because they allow for large amounts of information to be grouped together precisely. These phrases are built around the ‘head noun’ which is preceded by a combination of modifiers (e.g. quantifiers, determiners, adverbs, adjectives, and noun adjuncts) and followed by a combination of qualifiers (e.g. prepositional phrases and embedded clauses). Complex noun phrases that combine two or more individual noun phrases are commonplace in academia.

Non-Academic: Increasingly relying on plastics has damaged our oceans over a wide area for a long time.
Academic: Our increasing reliance on plastics has caused widespread long-term damage to our oceans.

Given their frequent use in academia, noun phrases are not only useful for effectively presenting information but also for making your writing feel more academic to the reader.

2) Gerunds & Infinitives

Another way of making your writing feel more academic to the reader is by employing gerunds and infinitives appropriately. Often replacing nouns in sentences, gerunds and infinitives usually serve similar purposes in writing and follow similar rules, however, they differ in certain ways.

When a gerund or infinitive appears before the main verb in a sentence, it serves as the subject; and when it appears after the main verb, it serves as the object. You should also note that an infinitive cannot be used directly after a preposition. When used incorrectly, gerunds and infinitives can muddy or even completely modify the meaning of a sentence.

Incorrect: To have become well versed in the ways of the landed gentry, Jane Austen was able to highlight, satirize and critique their contradictions and absurdities in her literary works.
Correct: Having become well versed in the ways of the landed gentry, Jane Austen was able to highlight, satirize and critique their contradictions and absurdities in her literary works.

As shown in the first example above, it is possible to use a series of gerund phrases or infinitives in one sentence: “to highlight, satirize and critique”. However, you need to make sure every item in the list or series is uniform: this is known as parallelism.

3) Parallelism

Parallelism improves the clarity, concision, and flow of your writing by ensuring related words, phrases and clauses are uniform in their grammatical structures. This has become instinctive for many native speakers, so it’s somewhat jarring when they encounter faulty parallelism in speech or writing.

To make things clear for the reader, you should be consistent in your use of adjective, noun, verb, and adverb forms within a sentence and pay close attention to your use of conjunctions, prepositions, and articles to determine if they can be made parallel or not.

Once you have a firm grasp of parallelism, you can use it functionally to make your writing more concise by removing unnecessary repetition; and creatively improving the rhetoric of your arguments. Many of the most memorable speeches from history employ rhetorical parallelism: “That’s one small step for man, one giant leap for mankind.” ~ Neil Armstrong, 1969

Faulty: The objectives of this study are to explore, measuring and explaining the relationship between internet access and economic growth.
Parallel: The objectives of this study are to explore, to measure and to explain the relationship between internet access and economic growth.
Concise: The objectives of this study are to explore, measure and explain the relationship between internet access and economic growth.

4) Active & passive voice

Since around the turn of the millennium, there has been a shift in academic writing away from the passive voice and towards the active voice. The change in consensus is mainly due to the fact the passive voice often obscures the agent in a situation and therefore the responsibility. The passive voice lends more objectivity to the writing, however, so it shouldn’t be outright dismissed.

When the subject of a sentence is being acted upon, the sentence is in the passive voice. When the subject of the sentence is doing the action, the sentence is in the active voice:

Active: During this period, the Romans established a complex network of roads and aqueducts around Europe.
Passive: During this period, a complex network of roads and aqueducts were established (by the Romans) around Europe.

When writing an essay, the passive voice is most suitable for describing a process in the Methodology or the findings of the study in the Results. The active voice is most suitable for describing the ideas and actions of others in the Discussion and Background, and it can also be used to break up the passive voice of the Methodology. The active voice allows you to be more precise in ascribing actions and ideas to agents, rather than presenting such things as objective truths.

Passive: A strong correlation between these two factors was found (in this study).
Active: Rhodes et al. argue that there is a strong correlation between these two factors.

5) Hedging

Hedging language is commonplace in academia. It can further improve the accuracy of your writing by expressing the level of certainty or uncertainty about something. Whether you are unsure about a claim being made or want to present an idea that lacks sufficient evidence to be a fact, hedging is the best way to write with caution.

The verbs ‘appear’ and ‘seem’ are commonly used for hedging: they are especially useful for presenting uncertainty in your own findings when using the passive voice. In the active voice, you can use reporting verbs like ‘suggest’, ‘argue’, and ‘claim’ to present the ideas of others that are yet to be verified.

Modal verbs like ‘could’, ‘may’ and ‘might’ are useful for hedging, softening claims that would appear too certain using the modal verb ‘will’. Adverbs are useful for softening claims, particularly ‘probably’, ‘potentially’, and ‘generally’.

Certain: A million humans will be living on Mars by the 2060s.
Hedged: Some claim that a million humans could potentially be living on Mars by the 2060s.

Bear in mind that these are general rules for academic writing. Different fields have different approaches to writing, so it’s a good idea to analyze the styles and structures employed by established academics in your field and mirror them in your own writing.