Body language carries as much respect as words, and the vocabulary differs by region. In East Asia, a bow, receiving items with both hands, and a slight lowering of the head before seniors speak volumes. Across South and Southeast Asia, the pressed-palms greeting, a slight stoop when passing between elders, and never pointing feet at people or shrines are the classics. In the Middle East and much of Africa, standing when an elder enters, placing a hand over the heart after a handshake, and giving or receiving with the right hand show courtesy.
Eye contact is the tricky one because it flips completely. In Western cultures, steady eye contact signals honesty and confidence, while in parts of Asia and Africa, prolonged eye contact with elders or superiors can read as challenge, and looking slightly down is the respectful posture.
Other near-universal signals: not sitting until invited, not crossing legs toward a senior person in formal settings, removing sunglasses when speaking to someone, and not keeping hands in pockets during introductions. Watch the room for a week and you will absorb most of it naturally.