Don gil de pantoja

Best of both worlds = disfrutar de lo bueno de las dos cosas

Don´t count your chickens before the hatch = no hacerse ilusiones antes de...

Caught between a rock and a hard place = entre la espada y la pared

To feel/to be under weather  = estar enferma 

Fit as a fiddle = estar bien de salud y en forma

Getting taste of your own medicine 

Giving someone the cold shoulder = ser borde con alguien

Hear it on/ through the grapevine = escuchar rumores 

no pain, no gain = sin esfuerzo no hay recompensa 

on the ball = ser espabilado