Culture is a way of living peculiar to a group of people.
Etiquette is the set rules that guide polite behaviour.
The challenge of blending the two is coming across as socially aware yet reasonably old fashioned, especially in the African culture.
A handshake may be the most acceptable way of greeting but it is rude when a young person initiates it to an elder. The least acceptable greeting is a curtsey from the lady and a bow from the gentleman.
Use of the left-hand is excusable in some social activities such as writing or dining but African culture interprets it as a bad omen. Extending a left hand (whether left-handed or not) to point, give a gift or receive a handshake is quite offensive.
The choice of dressing with certain colours is unadvisable. I attended a wedding a few weeks ago and could not but notice a guest draped in equal colours of black and red, from earring to shoe laces. Those colours could pass for the attire of a traditional worshipper of some sort. For a celebratory event, it is wise to avoid matching colours like these, especially in such equal proportions.
Giving gifts is always a thoughtful thing to do, except when your choice is so exotic that it is a rock. You will do well to keep your beach finds and present a more usual gift. Gifts like rocks speak volumes and your noble intentions are not so noble with such gifts.
As a guest, your options range from water to whatever your host can afford to set before you. Except you have an allergy to the food, you shouldn’t refuse it. African hospitality unfairly compels the host to serve you what you ‘want’ if you are so entitled to say, even when it’s not immediately available. Be an easy guest and eat what’s served with love.