The first requirement for being a gentleman is to be gentle.
Perfect composure of manner requires a peace of mind that is void of lies, cheating, swindling (running in debt). Owe no many anything. Avoid it like the plague. Debt is the most cruel of all oppressors.
Speak gently. A polite refusal or denial will would less than a rough, arrogant, and ungracious acceptance.
In private, watch your thoughts. In your family, watch your temper. In public, watch your tongue.
The truest secret to please all the world, is to have a humble opinion of yourself. True goodness is demonstrated by gentleness, courtesy, and humility. The truest virtues of a gentleman.