first of all
before anything else首先
One will be judged by one's speech first of all．首先，察其言而知其人。
If you want to speak good English， you should first of all listen to good English as often as possible．如果想英语说得好，首先应当尽可能地经常听好的英语。
Firt of all，let's read the new words．首先，让我们读生词。