The most important aspect for anyone who wants to be sucessful in any customer service position is to have the ability to be servile. Put simply if you are not a yes sir, no sir, three bags full, person you are not really suitable.
Some people, who are in the minority, are capable of modifying their behaviour to fit in with the above but a large majority are just not suitable for this type of work, you cannot train adults in basic courtesy and servility, it is something your parents should have done a long time ago.
Hang on a minute, you kidding me.
No offence but I have been in customer service for 10 years, and not once has anyone during any training told me to be yes sir, no sir 3 bags full, like some servent in the victorian ages.
I and crew I work with provide the best customer service possible, to help achive this is 'Adapting to different pax, and their needs'.
Yes it is good customer service to be polite, assist the pax with relevent requests and be there for them.
But at the same time it is important for pax to respect your position as a crew member and your primary role SAFETY.