There aren't many early game Whispers units, so the ideal opener would be a Bruiser start with some early game carry in the backline. A strong opener like that would be Skarner and Jax in the frontline, with Nidalee as AD item-holder. Level up to 4 at stage 2-1.
In the mid game, you get units like Sylas and Zyra available to you. That will give you Whispers 2. Try to make Zyra your focus in the mid game until you find Pantheon and Sy'fen in the late game. Level up to 6 at stage 3-2.