A writer who has published three books in French can still lose an hour to whether it should be "research" or "a research." The error is not a sign of weak English. It is a sign that English is asking a question the writer's first language never asked, and the answer is not in any dictionary.
Four patterns account for most of these slips. Each one is learnable in a sitting, and each one improves a draft immediately.
A, an, and the: the three-way choice
English forces a decision on nearly every noun: is this thing new to the reader, already known, or one of a kind? Other languages split the same job differently, which is why the rule feels arbitrary even when it is explained.
The short version is a matter of shared knowledge.
"A" or "an" introduces something the reader has not met yet. It means "one of many, and you do not know which."
I read a report on shipping costs.
"The" points to something the reader can identify. That identification can come from earlier in the text, from the situation, or from the fact that only one exists.
I read the report you sent.
No article marks an uncountable noun used in general, or a plural used in general.
Research on shipping costs is thin. Reports on shipping costs are thin.
The failure pattern is usually using "the" for a first mention, because the writer knows which report they mean. The reader does not.
Not: I found the error in the code. Better: I found an error in the code. (First mention.)
The reverse failure is dropping "the" for a specific thing.
Not: Please send report by Friday. Better: Please send the report by Friday.
Prepositions are idioms, not logic
Prepositions cannot be reasoned out. They are attached to words by convention, and the convention differs between languages and even between dialects of English.
You depend on something, but you rely on it and count on it. You are interested in something, but curious about it. You agree with a person and agree to a proposal. You suffer from a condition and benefit from a treatment.
The practical fix is a habit rather than a rule: when you learn a new verb, learn its preposition with it. Keep a running list of the ones you get wrong. Most writers have about a dozen, and they repeat.
A second useful habit: check whether the sentence needs the preposition at all. Phrasal verbs and their Latinate cousins often differ.
Discuss the plan (no preposition). Talk about the plan (preposition required).
Explain the decision (no preposition). Give an explanation of the decision (preposition required).
When a sentence feels stiff, a preposition that should not be there is often the cause.
Countable and uncountable nouns
English divides nouns into those you can count (two chairs, three ideas) and those you cannot (water, advice, information, research, equipment, furniture, feedback). Uncountable nouns take a singular verb, no plural, and no "a."
Not: She gave me some useful advices. Better: She gave me some useful advice.
Not: The equipments are new. Better: The equipment is new.
Not: I need an information about the schedule. Better: I need information about the schedule. / I need a piece of information about the schedule.
The last repair is worth remembering. When you need to count an uncountable noun, use a counter: a piece of advice, two items of furniture, three pieces of equipment, a bit of feedback. This works in every register.
Some nouns switch category depending on meaning. "Paper" is uncountable as material and countable as a newspaper or an academic article. "Experience" is uncountable as accumulated knowledge and countable as a single event. "Coffee" is uncountable as a substance and countable as a cup of it.
Not: I have many experiences in marketing. Better: I have a lot of experience in marketing.
Verb patterns: the word after the verb
English verbs disagree about what can follow them. Some take a bare infinitive, some take "to," some take a gerund, some take a clause. There is no way to predict the pattern from the meaning, so it has to be learned word by word.
She suggested going early. (not "to go") She decided to go early. (not "going") She recommended that we go early. She avoided going early.
The pattern often changes with the meaning.
I remember locking the door. (a memory of an action) I remembered to lock the door. (I did not forget)
I stopped smoking. (I quit) I stopped to smoke. (I paused in order to smoke)
A thesaurus makes this harder rather than easier, because it offers synonyms with different patterns. "Suggest," "recommend," "propose," and "advise" all mean roughly the same thing and take four different structures. Choose the verb first, then look up its pattern, rather than swapping one for another mid-sentence.
A routine that catches most of it
Read the draft once looking only at noun phrases. For each one, ask the three-way article question. Do not fix anything else on this pass.
Read it again looking only at verbs and the words immediately after them. Check the preposition and the pattern.
Then run a final read for meaning, because the point of all this is not correctness. It is that readers stop noticing the machinery and start following the argument.
A grammar checker will flag some of these patterns, especially article use before specific nouns and the most common preposition pairings. It will not know what you meant, and it will sometimes be wrong. Treat its suggestions as questions, not corrections.
None of these habits require you to sound less like yourself. The goal is to remove the small collisions that make a reader pause, so that the sentences you actually care about land cleanly. That is the same goal every writer has, in every language.