Some embarrasing mistakes you can make learning Vietnamese
01. Calling your wife/husband/friends' mother a "ghost".
Má with low constricted tone (Mother) vs Ma with level tone (Ghost)
02. Calling your wife/husband/friends' uncle a "dog" or "breasts".
Chú with "ch" initial consonant (Uncle in father's side) vs dú with "y" initial consonant.
Cậu with low constricted tone (Uncle in mother's side) vs Cẩu with falling rising tone (A dog)
03. Calling your wife/husband/friends' father a "cow" or "grandmother"
"Bố" with the rising tone and the strange letter "ô", different from the letter "o" vs "Bò" with the falling tone and the letter "o"
"Ba" with the level tone vs "Bà" with the falling tone.
Some common mistakes you can make learning Vietnamese
01. I'm fine, too & I'm not fine
95% of my students said "Cũng" (too) as "Không" (no).
Try to practise your pronunciation with these two words.
02. Some numbers
Alhough rising tone is an easy tone for my students to say, most of them always forget the rising tone of the numbers: six, eight and nine. So please go up with Sáu, Tám and Chín