If you have "Harpie Lady Sisters" in your deck, try to have at least the same number of "Elegant Egotist", since Harpie Lady Sisters cannot be initially Summoned by any other means.
If your opponent controls a "Harpie Lady", you can use this card's effect to level the playing field.
If you have "Harpie Lady Sisters," try to use this card mostly to summon her, unless you need the effect of another "Harpie Lady" monster, such as "Harpie Lady 1." Keep in mind that others Harpies, unlike "Harpie Lady Sisters" can be Normal Summoned, so you can use them as soon as you draw them.
However, you can use "Elegant Egotist" to summon other "Harpie Lady" monsters when one of them is on the field, as at that point their names will become "Harpie Lady."
Use cards such as Spell Reproduction to take back "Elegant Egotist" from your Graveyard. This way, you can use it more then 3 times in a duel.
For the best results, utilize "Hysteric Sign"; upon activation it will either search this card from your Deck or recover it from your Graveyard, with the added bonus of searching out "Harpie" cards from your Deck when it's destroyed.
If you have a "Harpie Lady" monster in your hand, and plan on drawing "Elegant Egotist" to summon another "Harpie Lady" monster with her, try not to risk her by summoning her to the field before you have it in hand; while "Harpie" monsters are at their strongest in large groups, they are much weaker individually, so it may be in your best interest to hold back until you can swarm the field.