A genuine compliment will suffuse the recipient with positive feelings, and oils the wheels of social intercourse. Only offer compliments when you believe them, and don’t over-compliment – you will look like an insincere flatterer.
Stick to specifics; vague, overgeneralised compliments are easily devalued. Never damn with faint praise, or give a compliment with one hand and take away with the other.
Try and give the compliment in a timely manner – don’t wait until you are leaving a dinner party to praise the food, for example – a spontaneous response feels more genuine.
If you are the recipient of a compliment, smile and say thank you. Don’t denigrate yourself, or take it as a cue for boasting. Never retaliate with a knee-jerk compliment back. The recipient will, rightly, regard it with suspicion.