I will take advantage of today being Friday the 13th to write a few words about Chinese superstitions. As mentioned several times across the rule book, Chinese people are extremely superstitious. Confucian characters less so, but the scholar who scorns superstitious commoners during the day may very well go in disguise to the home of a necromancer during the night...
Many Chinese superstitious are based on homophonous Chinese characters.
The main superstition revolves around the characters for 'death' 死 and for the number 'four' 四 being both pronounced [sɨ]. The number four is hence avoided at all costs in writing, conversation, etc. (much like the number 13 in the US).
Superstition is not always negative, however: the character for 'prosperity' 發 is pronounced [fa], which is similar to the pronunciation of the number 'eight' 八: [pa]. The number 8 is viewed as such an auspicious number that many Chinese go to great lengths to secure a "number eight" in whatever they are doing.
The characters for 'surplus' 余 and for 'fish' 魚 are both pronounced [y], so fish are considered to be lucky. That's why fish feature so highly in Chinese art, and lots of Chinese people have pictures of fish on their walls. In the same vein, lotus flowers and boxes are associated with weddings because they are both pronounced [xɤ] – the same as the character for 'harmony' 和. In some areas, it was traditional to empty seeds or fruit onto a newly wed couple's bed because fruits and nuts contain the character 子 which also means 'son'. Jujubes and chestnuts are particularly lucky because they are the homonyms of 'early son' and 'produce a son' respectively. Bats are auspicious because the word sounds the same as 'happiness' and deer are because they sound the same as 'wealth'.
Many other superstitions are based on colour.
Red and gold are both extremely auspicious. Red is extensively used at weddings, birthdays etc. However, writing in red can be seen as offensive because it is the colour used for the ink that scares away guǐ-monsters on Daoist amulets.
White is the colour of death and is thus avoided. Yellow is the colour of the emperor and is hence forbidden for anyone else.
Jade is highly valued, and not only for its beauty. According to Chinese superstition, jade can also bring good fortune and ward off evil spirits, hence the popularity of jade pendants and bracelets.