先…然后/再…: first… then…
固定格式 / fixed patterns
Tone colorsā tone 1á tone 2ǎ tone 3à tone 4a neutral
先 + V1，然后 (再) + V2
To describe steps in order, put 先 (first) before the first action, and 然后 (then) and/or 再 before the second.
先 and 再 are adverbs: they go after the subject, before the verb. 然后 is a connector at the start of the clause.
You can chain them: 先…，然后…，最后… (first… then… finally…).
Examples
我们先去上海，然后去杭州。
Wǒmen xiān qù Shànghǎi, ránhòu qù Hángzhōu.We'll go to Shanghai first, then Hangzhou.
你先吃饭，再做作业。
Nǐ xiān chī fàn, zài zuò zuòyè.Eat first, then do your homework.
我先买票，然后再订酒店。
Wǒ xiān mǎi piào, ránhòu zài dìng jiǔdiàn.I'll buy the tickets first, then book the hotel.
先洗手，然后吃饭，最后休息。
Xiān xǐ shǒu, ránhòu chī fàn, zuìhòu xiūxi.First wash your hands, then eat, and finally rest.
Common mistakes
✗ 先我去上海 → ✓ 我先去上海 (先 after the subject).
✗ 我然后去杭州 → ✓ 然后我去杭州 / 我再去杭州.