Coherence
To help your audience of readers to easily follow your thoughts, your writing must be coherent.
The techniques below show you how coherence is established.
Order of ideas\support
Paragraphs within the essay  must have an order that a reader can follow. It is also helpful
to order sentences within a paragraph to make it easy for the reader.
Here are some (but not all-create you own) standard ways to order an essay\paragraph.

Space order - used for physical descriptions

Time order - used for telling a story, an anecdote, an event etc.

Order of Importance - used for illustration, cause/effect, classification/ argumentation etc.

General to specific  -  used for explanations, information, almost anything

Obvious to hidden - used to highlight your point, to alert reader to unknown etc

Transitions: 
words\phrases\sentences
Depending on order and rhetorical method you choose, you must include transitions to make
it clear what it is. Below is  list of possible transitions to use to establish order\method in your writing.

space order

above, across, against, along, alongside , amid among, around, away from, back of , behind, below,  beneath, beside, between , beyond, by, down , in front of, inside, into, near, off, onto . on top of, outside, over, throughout, to the right, under

time order

about, after a short while, after , afterwards, all of a sudden, all the while, as soon as, at , at that time, before , by that time, by then, during, finally, first, immediately, in a few hours,  in the meantime, in those days, later, meanwhile, next, next week, prior to , second, since,  soon, soon, suddenly, then , then, thereafter, thereupon, third, till,  today, tomorrow, until, until then, when , when, whenever, while, yesterday

importance

again, as an example , for instance, for this reason, in fact, indeed, matter of fact, more important, more importantly, not very seriously, once again, once more, seriously, specifically, the best was, to be sure, to emphasize, to repeat, with this in mind

add information]

additionally, again, along with, also, and, another, as well, besides, equally important, finally, for example, for instance, further, furthermore, furthermore, in addition, likewise, moreover, next, together with

contrast things

although, as opposed, but, conversely , counter to, even so, even though, however, in contrast, in the meantime, nevertheless, nonetheless, on the contrary, on the other hand, otherwise, still, then again, though , while, yet

comparison

also, although, as , as if, as though, even though,  in contrast, in the same way, like , likewise, on the contrary, on the other, hand, similarly, though

conclude or summarize

accordingly, all in all, as a result, consequently, due to, finally, in short, in summary, therefore, thus, to sum it up

show condition

as long as, as soon as, in case, in order to, provided that, unless, when
Pronoun References
Pronouns should be used correctly. Antecedents (words they replace) should be clear.
They should agree in: number, gender, case.
Parallel Structure
Sentences must be constructed with accurate: verbs, modifiers, clauses, word selection
and structure that is constant and easy to follow.