Both the subsequent and prior actions will be independent clauses and thus end, like all sentences, in a verb. The verb for the subsequent action must be the present tense dictionary form. This is a little confusing for English-speakers because in English we put each clause in the tense corresponding to the timing of the action relative to the present. In other words, we would say:
Before I went to work I bought some cigarettes.
In Japanese, however, the tense of the first clause is independent from the tense of the latter.
仕事に行く前に、コーヒーを飲む。
Before I go to work I will drink coffee.
仕事に行く前に、コーヒーを飲んだ。
Before I went to work I drank coffee.
As a native English speaker there is an innate desire to say:
仕事に行った前に、コーヒーを飲んだ。(✘)
Unfortunately, this is not correct. Some more example sentences:
家を出る前に、電気を消します。
Turn off the lights before leaving the house.
道路を渡る前に、左右を確認します。
Look left and right before crossing the street.
暗くなる前に、帰ってきてください。
Please come back home before it gets dark.
Using Nouns
For nouns, we need to connect them using the possessive particle, の.
説明会の前に、受付で自分の名前を登録してください。
Before the seminar please register your name at the reception.
食事の前に、手を洗います。
Before a meal, I wash my hands.
Time and Durations (Dropping the の)
There is one critical exception to the noun rule above. When using a specific duration or quantity of time (e.g., minutes, days, years) or a specific clock time, the の particle is dropped. 前に attaches directly to the word. When used with a duration, it translates to “ago”.