Vanilla Harpie decks uses normal Harpies, and Mai's exclusive skill Harpies' Hunting Ground. The combination of Order to Charge, and the ability to destroy your opponent's backrow, makes it quite versatile, which can then be often updated with newer cards from new boxes.
Generally, the way you play Harpie decks is to simply summon the Harpies to destroy your opponent's backrow before attacking their monsters. This will allow you to attack your opponent's monster without having to worry about their spell/trap cards. If your opponent summons a stronger monster with a higher attack, then you use Order to Charge to take them down.
Harpie's Hunting Ground
Harpies' Hunting Ground is what makes Harpie decks quite strong, but it can potentially be a weakness as well. Since Harpie decks are quite common, people have been bringing cards to counter this field spell. If your opponent has no spell/trap card, summoning a Harpie monster will activate its ability, forcing you to choose your own card. Cards like Security Orb, and Wild Tornado are also getting more common, making you think twice instead of blindly choosing to destroy your opponent's spell/trap card(s).
The non-effect Harpie monsters are often used because of Order to Charge, which is a really good card that allows you to confidently summon this card, despite its low attack. It can be used to destroy most monster your opponent summons, and can be activated during their turn. But you can use the other different Harpie monsters, which offers different effects and can be useful depending on your playstyle.
Special summoning from the grave
The effect of Harpies' Hunting Ground is activated even when your Harpie monsters are special summoned from the graveyard.
Knight of the Red Lotus can be tribute summoned, or special summoned. It can activate its ability once per turn, so if you want to attack your opponent's monster, it's better to use the lower level first, in case it gets destroyed. This is so you can special summon it again on your next turn.
Soul Resurrection can only special summon normal monsters in defense position. Use it at the end of your opponent's turn to make sure it doesn't get attacked/destroyed, and allows you to switch to attack position on your next turn.
Other vanilla beaters
Since you can only put 3 Harpie monsters, you will need to use other monsters in the deck. If you want to use Order to Charge, it's better to put normal monsters like Sonic Duck, or Blazing Inpachi since they have high attack. They both have low defense, but it won't matter that much if you have an Order to Charge at the ready.
Tips for using the deck
Summon a Harpie monster if your opponent sets spell/trap cards, so you can destroy a spell/trap card your opponent controls by the effect of the field spell.
If you don't want to risk destroying your opponent's Wild Tornado, or Security Orb, then it's better to destroy their field spell instead, or destroy your own Wild Tornado.
Guard the "Harpie's Hunting Ground" field spell against Twister or other spell removal by using counter trap cards, or bring Minefieldriller.
This is an expensive deck, had 3 resets in two different packs with 3 UR each, so basically the most expensive HHG i ever saw, if you want win the game, add 1 reliquished, remove the extra kuriboh and MW, and if you millennium scorpion add 1, too many econ, you dont need many
Some choices don't make sense. First: drop Nobleman (you'll rely on field spell effect to destroy the set cards), Riryoku (kind of a dead card), Wild Tornado (if you have another OTC) adn Jerry Beans (afraid of 4-star Ladybug? Then put another Duck).
Second: your deck has little to none defense (Econ, Dollar Wall and Kurboh only). Third: Why this Effect Harpie and not the Hottest one(+300atk)?
Will be very hard to draw a harpie with this deck, add 2 or 3 elegant egotist, add at least one more eliminating the league, take off beans or other beater to add one more WT, remember, in HHG, have good cards means nothing if the enemy get a strong monster and destroy your field spell, you need to be able to trap kill high stats monsters