1. 开始(交谈);建立(友谊);开始(来往)
When you strike up a conversation or friendship with someone, you begin one.

2. 开始演奏
When musicians strike up a piece of music, or when music strikes up, the music begins.

1. begin

e.g. strike up a conversation
strike up a friendship

2. start playing

e.g. The musicians struck up a tune

Synonym: sound off