What cultural faux pas should I try to avoid making in Zhuhai?

"It is important to remember that, in Zhuhai, guests should always take their shoes off when entering someone's home. Keeping one's hands out of one's pockets and not spitting on the sidewalks are important cultural norms to observe. Displays of public affection, such as holding hands, are considered inappropriate in many parts of Zhuhai. Furthermore, always treat the elderly with respect, as this is seen as a sign of reverence and politeness. Finally, it is also considered disrespectful to give gifts with the number four, as this is viewed as an unlucky number in Chinese culture," mentioned another expat when asked about moving to Zhuhai, China, China.