Just to add a bit more.

If someone holds chopsticks right towards the end opposite the food end, he / she is working far from home. I've tried observing this and to my surprise, a great majority do work far from home.

To use chopsticks of uneven length is bad luck. The Chinese refers, in polite circles, to death as "3 long, 2 short"; which is another way of mentioning a coffin, which, discounting the base part, is made up of 3 long side planks and 2 short end pieces.

Left-handedness was frown upon by the old chinese and being born left-handed, I was forced to use my right hand for chopsticks and pen carrying; everything else, I used my left.

When handing a pair to a guest, always use two hands, with the food-end pointing towards your own right horizontally.

Silver chopsticks were used in order to detect poison, which if present, turns black.

Chopsticks were never put on ancestral-worshipping or any altars.

It is bad Chinese manners to lay them horizontally on the lid of your bowl, because this is what beggars do as they do not eat on tables or at least clean tables and so do not have clean places to lay them while eating.

To the Japanese, sticking them into rice or food and leaving them there is a great no-no, as this is what they do when presenting food to the dead.

If when you first hold a pair and the ends are not even (which often happens), do not tap the food-end on the table to align them; tap them gently on your other palm.

Hold the other open palm just underneath your chin while putting food into your slightly opened mouth with chopsticks is the height of refinement. Watch a beautiful Japanese lady do it and you'll see what I mean.

And finally to test if the temperature of deep-frying oil is right, stick a bamboo chopsitck in, and if lots of little bubbles form around the stick, it is just about right for frying your spring roll.
I'll rather be happy than right, anytime.