Which proverb means "to be grateful for what you have, rather than always wanting more"?

Which proverb means "it's better to have a small, certain advantage than a larger, uncertain one"?

Which proverb means "it's better to deal with a problem immediately rather than waiting and letting it get worse"?

Which proverb means "to not let your emotions control your actions or decisions"?

Which proverb means "to be careful not to do or say something that could offend or upset someone"?