first off anything else首先；起先；开始时。
killer n. (AMUSEMENT)
= a very entertaining or skilful person, story, or performance令人着迷的人（或故事）；技能出色的人（或表演）。

【例句】
I said that first off I wanted an apology.
我说过，首先得向我道歉。

Dizzy was a real killer on the trumpet.
迪齐是个非常出色的小号手。