Putting events in order
Once you can talk about the past with 了, you'll want to put two or more actions in order. Mandarin uses a small set of connectors: 然后 (then, after that), 先 X 再 Y (first X, then Y), 以前 (before), 以后 (after). The crucial word-order point: time-when phrases — 昨天, 今天早上, 回家以后 — sit at the FRONT of the sentence (or right after the subject), never at the end. The English habit of saying 'I called you after I got home' has to be flipped: in Mandarin, 回家以后我给你打电话.
然后 — 'then, and after that'
然后 ránhòu links two clauses in sequence. Pattern: clause 1, 然后 + clause 2. 我吃了饭,然后去学校。 = I ate, then went to school. 她看了书,然后睡觉了。 = She read, then went to sleep. 然后 sits at the START of the second clause, BEFORE its subject (or with no subject if it's the same as in clause 1). It does NOT translate as 'and' — for plain 'and' between clauses, Mandarin usually just uses a comma.
先 X 再 Y — 'first X, then Y'
When the order is being emphasized — first this, THEN that — use 先 + verb 1, 再 + verb 2. 先 xiān = first, 再 zài = then (only in this 'and-then' sense). 我先吃饭,再看电影。 = I'll eat first, then watch a movie. 你先做作业,再玩。 = Do your homework first, then play. Both 先 and 再 sit BEFORE their verbs, after the subject. This is the everyday way to schedule two steps.
以前 / 以后 — before and after an event
以前 yǐqián = before. 以后 yǐhòu = after. They go AFTER the event (the opposite of English): 吃饭以前 = before eating, 吃饭以后 = after eating, 回家以后 = after going home, 去中国以前 = before going to China. The whole event + 以前/以后 chunk acts as a time phrase and sits at the FRONT of the main clause: 回家以后我给妈妈打电话。 = After going home, I called mom. By itself, 以前 can also mean 'in the past / before' — 我以前不喝咖啡。 = I didn't drink coffee before.
Time-when always goes before the verb
This rule from lesson 7 is doubly important now. 昨天我吃了饭,然后看了电影。 = Yesterday I ate, then watched a movie. 今天早上我先喝了咖啡,再去了学校。 = This morning I drank coffee first, then went to school. NEVER put the time word at the end English-style: not 我吃了饭昨天. Two safe slots: at the very front, or right after the subject. With multiple time markers, the bigger one comes first: 昨天晚上 (yesterday evening), 今年五月 (this May).
Telling a small story
Stack these tools: 昨天我先去了书店,买了三本书,然后回家。回家以后,我吃了饭,看了一个电影。 = Yesterday I first went to the bookstore and bought three books, then went home. After getting home, I ate and watched a movie. Notice how 了 marks each completed action and the connectors do the sequencing work. Mandarin storytelling really is just clause-clause-clause linked by these little words.
