i think a couple of lessons would be of use - but the main focus should be on the pronunciation of words.

My first visit to China didn't give me any problems asking for help (people are willing to assist)... but my pronunciation was the main issue.

You might think a street is pronounced in a certain way, but no one may understand you. Changing the pronunciation of the vowel or understanding how consonants work and all of a sudden you'll get directions.

For me, better pronunciation, and the basics for a taxi were the key to a fairly happy time.

Essential? By no means. But if you just want to hop in a taxi after a long day out to go to the next place it will make it easier.