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

"It is important to be mindful of cultural differences when visiting Iceland. It is considered rude to be late for appointments or social engagements, so it is important to be punctual. It is also important to respect the Icelandic language and not to speak loudly in public. Additionally, it is important to respect the Icelandic nature and not to litter or leave any trace of your presence. It is also important to respect the privacy of others and not to take pictures of people without their permission. Finally, it is important to dress appropriately and not to wear revealing clothing in public," mentioned another expat when asked about moving to Iceland.