The 12 English Grammar Rules That Fix Most Mistakes

Priya Sharma

Priya Sharma writes English learning guides for ESL students. Pune-based language enthusiast.

Visual representation of the voice · not a photographic portrait

Quick answer: Most English mistakes come from a small group of rules: missing subjects, the -s on he, she and it, do and does in questions, past simple versus present perfect, articles, word order, and verbs followed by -ing or to. Fix word order and tense first, then the smaller details.↗ Share on X

You do not need to learn all of English grammar to stop making mistakes. A small group of rules causes most of the errors learners actually make in conversation and writing. Learn these twelve, in this order, and the majority of your errors disappear — even if you never open a grammar book again.

Each rule below has the pattern, the mistake people make, and one thing to practise today.

1. Every sentence needs a subject and a verb

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English does not let you drop the subject, even when it is obvious.

• Wrong: *Is raining.* · *Is very difficult to learn.*
• Right: It is raining. · It is very difficult to learn.

Many languages allow the subject to be left out. English does not. When the sentence has no real subject, English uses it or there as a placeholder.

Practise: write five sentences about the weather and today's plans. Check that every single one starts with a subject.

2. Add -s to the verb with he, she, and it

This is the most common mistake in the world, and the easiest to fix.

• Wrong: *She work in a bank.*
• Right: She works in a bank.

Practise: say five sentences about a friend or family member out loud. Listen for the -s.

3. Use do and does to make questions and negatives

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In the present simple, you do not add a question word to the main verb. You use do or does, and the main verb goes back to its plain form.

• Wrong: *You like coffee?* · *She not like coffee.* · *Does she likes coffee?*
• Right: Do you like coffee? · She does not like coffee. · Does she like coffee?

Notice the trap: once you use does, the -s has already been used. The main verb stays plain.

4. Choose the right past form

English has two past forms that learners mix up constantly.

The key test: if you say when, use the past simple. "Yesterday", "last year", "in 2019", "two days ago" all force the past simple.

• Wrong: *I have seen him yesterday.*
• Right: I saw him yesterday.

5. Articles: a, an, and the

Three questions decide it, in order.

1. Is it the first time you mention this thing, and the listener does not know which one? → a or an.

2. Does the listener already know which one you mean? → the.

3. Is it a general idea, or something uncountable? → often no article at all.

• I bought a car. The car is red. (First mention, then known.)
• I like music. (General — no article.)
• The sun is bright. (Only one exists.)

Use an before a vowel *sound*: an apple, an hour, an honest man. But: a university, a European city — because those start with a "y" sound.

6. Countable and uncountable words

Some words cannot be counted, and they never take a plural -s.

• Wrong: *I need some advices.* · *He gave me many informations.*
• Right: I need some advice. · He gave me a lot of information.

Also: use many and few with countable things, and much and little with uncountable ones. A lot of works with both, which is why it is safe when you are unsure.

7. Adjectives come before the noun and never take -s

• Wrong: *a car red* · *three reds cars* · *the peoples are happy*
• Right: a red car · three red cars · the people are happy

Adjectives in English do not change for number or gender. Ever. This one rule saves speakers of Romance languages a huge number of errors.

8. Word order: subject, verb, object

English word order is fixed, and moving things around changes the meaning or breaks the sentence.

Subject → verb → object → place → time.

• I (subject) drank (verb) coffee (object) at home (place) this morning (time).

Adverbs of frequency — always, usually, often, sometimes, never — go before the main verb, but after the verb "to be".

• I always eat breakfast. · She is always late.

9. Prepositions of time: in, on, at

Learners guess these. There is a pattern.

Think of it as zooming out: at is a point, on is a day, in is a container of days.

10. Some verbs take -ing, others take to

There is no logic here — it is memory. Start with the most common ones.

• Wrong: *I enjoy to read.* · *I want reading.*
• Right: I enjoy reading. · I want to read.

After a preposition, always use -ing: "good at cooking", "interested in learning", "before going".

11. Modal verbs never take -s or "to"

Can, could, will, would, may, might, must, should.

• Wrong: *She can to swim.* · *He musts go.* · *I will to call you.*
• Right: She can swim. · He must go. · I will call you.

One modal per verb, plain form after it. That is the whole rule.

12. Say "I am" for age, hunger, and cold

Some states use "to be" in English where other languages use "to have".

• Wrong: *I have 30 years.* · *I have hunger.* · *I have cold.*
• Right: I am 30. · I am hungry. · I am cold.

Which mistakes should you fix first?

Not all errors cost you the same. Some make you hard to understand; others just sound slightly off. Fix them in this order.

Work from the top. Perfecting articles while your word order is wrong is effort spent in the wrong place.

A four-week routine that actually sticks

Fifteen minutes a day beats three hours on Sunday. Grammar is a habit, not information.

The fastest way to find your own mistakes

Write a short paragraph, then read it out loud, slowly. Reading aloud catches errors your eyes skip over — a missing -s, a missing article, a verb in the wrong place. Then check it against just the list of twelve rules above, one rule at a time. Most learners find the same three mistakes repeating, which means they only really have three problems, not a hundred.

Your next step

Write five sentences right now: two about what you did yesterday, two about what you do every day, and one about what you plan to do next month. Then check each one against rules 2, 4, and 10. Those three rules alone account for the errors most learners repeat every single day.

FAQ

What is the most common English grammar mistake?

Forgetting the -s on the verb after he, she or it. Say she works, he lives, it goes. It is very noticeable to native speakers and one of the quickest errors to correct.

When do I use the past simple instead of the present perfect?

If you say when it happened, use the past simple. Words like yesterday, last year and two days ago force it. Say I saw him yesterday, not I have seen him yesterday.

How do I know whether to use in, on or at for time?

Use at for a point in time such as at 7 o'clock, on for a day or date such as on Monday, and in for a longer period such as in July or in 2026.