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

"It is important to be mindful of local customs and etiquette when visiting Cascais. It is considered impolite to be late for appointments or social engagements, so it is important to arrive on time. It is also important to dress modestly and conservatively, especially when visiting religious sites. It is also important to be respectful of local traditions and customs, such as not eating in public during religious holidays. Additionally, it is important to be aware of the local language and to avoid speaking loudly in public. Finally, it is important to be respectful of the environment and to avoid littering," mentioned another expat when asked about moving to Cascais, Portugal.