Some languages offer various methods for someone to address someone older than themselves if you are speaking the language. You never give anything to someone, particularly an adult or someone older than you, with your left hand. It is seen as an insult.
If someone is seated with their legs stretched out, you do not cross or leap over them. It is considered unlucky.
In non-Igbo communities, avoid shaking hands with elders and elderly people. It’s impolite to act in this manner. Can you maybe lower your head a little? Kneeling or genuflecting for ladies and prostrating for males (particularly among the Yoruba) is the norm. You may not need to do it as well, but just show some respect while meeting elderly folks. In large cities or metropolitan regions, you may get away with not doing that since they are less conventional.
When entering a home in the mainly Muslim North, you must notify the ladies ahead of time that you will be coming so that they can prepare (cover themselves up). Some Islamic traditions compel women to cover their hair and body in front of other males, which is common in the North. Before entering, knock on the door and wait for a response. They will ask you to wait while they tell the ladies. Don’t get upset if you have to wait.