How to express thanks in words?

Could you elaborate on the various ways one can express gratitude through words, both in formal and informal settings? Is there a specific phrasing or tone that is considered more effective in conveying sincere appreciation? Additionally, how can one tailor their expressions of thanks to the nature of the favor received or the relationship with the person being thanked? Lastly, are there any cultural nuances or differences to consider when expressing gratitude in different parts of the world?