English t and d sit between the two Hindi sounds, so you must choose a side every time.

For the dental sounds त द, the tongue tip touches the back of your upper teeth. For the retroflex ट ड, curl the tongue back so the underside touches the roof of the mouth. Say तीन and टीन back to back twenty times; the difference will feel exaggerated at first and that is correct.

Aspirated consonants are released with an audible puff of air, and Hindi treats them as entirely different letters.

Hold a sheet of paper in front of your mouth. For क प ब it should barely move; for ख फ भ it should visibly flutter. English speakers actually aspirate word-initial consonants already, so the harder task is usually suppressing the puff on the unaspirated ones.

Short and long vowels are separate phonemes in Hindi and change the word entirely.

Hold the long vowels for roughly twice the duration of the short ones. English speakers routinely produce something in between, which leaves the listener guessing. Exaggerate the length while practising — in normal speech it will settle to the right value on its own.

The chandrabindu and bindu nasalise a vowel through the nose without adding a full n sound.

The है / हैं pair matters constantly, because dropping the nasal turns a respectful plural into a singular and makes आप हैं sound wrong. Practise by holding your nose lightly — if the sound is properly nasalised you will feel the vibration blocked.

Five minutes a day, one feature at a time. Say each minimal pair ten times alternating, then record yourself and listen back — hearing your own recording is uncomfortable and far more informative than listening while you speak. Work on one feature for a full week before moving to the next.

It also helps to know which errors actually cost you comprehension and which merely mark you as foreign. Vowel length and the nasals genuinely change words, so errors there can make a sentence unintelligible. Retroflex and aspiration mistakes rarely stop you being understood — they simply sound foreign. If your time is limited, fix length and nasals first, since those are the ones that cause listeners to misunderstand rather than just to notice.

• Using an English t or d, which sits between the dental and retroflex and matches neither.
• Aspirating unaspirated consonants out of English habit.
• Producing a vowel length halfway between short and long.
• Adding a full n instead of nasalising the vowel.
• Practising all four features at once instead of one per week.

1. Say तीन and टीन alternately twenty times.
2. Do the paper test with कान and ख़ान, पल and फल.
3. Practise कल and काल, दिन and दीन with exaggerated length.
4. Say है and हैं while holding your nose to check the nasal.
5. Record one minute of reading and compare it with the audio.