Here are some things I've learned from men who have practiced good harem etiquette.
It's not clever to provoke a woman's jealousy or insecurity. Flattering though it may be to a man's ego, her damaged vanity can brew silently and turn into a very effective form of hatred that will come back to bite you. A man who uses a woman's sexual jealousy to reassure himself doesn't belong in a harem. If you enjoy feeling clever, take some pride in preventing jealousy by making each woman you're involved with feel uniquely attractive. Stay on message.