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

"When visiting Hai Phong, it's important to respect local customs and traditions to avoid causing offense. Avoid public displays of affection, as they are considered inappropriate in Vietnamese culture. It's also considered rude to touch someone's head or pass anything over someone's head, as the head is considered the highest part of the body and sacred. When visiting religious sites, dress modestly and remove your shoes before entering. Pointing with your finger is considered rude, instead use your whole hand to gesture. Avoid discussing sensitive topics such as politics, the Vietnam War, and comparisons between Vietnam and other countries. In Vietnamese culture, it's considered impolite to show anger or frustration in public. Try to remain calm and composed in all situations. Also, remember to use both hands when giving or receiving something, especially business cards or gifts. Avoid taking photographs of military installations or people without their permission. It's also important to respect the local environment and not litter. When dining, wait to be shown where to sit and avoid sticking your chopsticks upright in your bowl, as this is associated with death. Lastly, tipping is not customary in Vietnam, but it is appreciated, especially in the service industry," remarked another expat who made the move to Hai Phong, Vietnam.