For homes, the near-universal sequence across Asia, the Middle East, Scandinavia, and much of the world: shoes off at the door, so watch for the shoe pile or simply ask, and wear decent socks. Bring a small gift where customary, greet the eldest present first, sit where invited, and accept the tea or refreshments offered, since declining hospitality outright can disappoint hosts in cultures where feeding guests is love. Compliment the home and the food, and do not wander into rooms uninvited.
Sacred sites run stricter and vary by faith. Common denominators: modest dress covering shoulders and knees, quiet voices, phones silenced, and no photography where forbidden or where people are worshipping. Mosques require shoes off and head coverings for women, with some closed to non-worshippers at prayer times. Hindu and Buddhist temples expect shoes off, no touching of statues, and often clockwise circulation; some bar leather. Gurdwaras require head coverings for all and shoes off. Churches, particularly Orthodox and Catholic, expect covered shoulders and hushed behaviour, with head coverings in some traditions.
Everywhere, the master rules are the same: observe what locals do, follow attendants' guidance without argument, and when unsure, ask quietly. Sincere respect is recognised instantly in every tradition, and it opens doors that guidebooks cannot.