Learn Hardcore Russian: Этот автор раньше был юристом, но потом стал писателем. - This author used to be a lawyer, but then became a writer.

In Russian, when you say that someone is / was / becomes a profession, role, nationality, etc., you normally use the instrumental case after verbs like быть (to be) and стать (to become).

Он был юристом. – He was a lawyer.
Он стал писателем. – He became a writer.

So:

юрист (nominative) → юристом (instrumental, -ом)
писатель (nominative) → писателем (instrumental, -ем)

Pattern to remember:

After был / будет / стал
- profession/role → instrumental is the default, natural choice.

Can I say был юрист and стал писатель instead of был юристом and стал писателем?

For a learner, you should stick to the instrumental: был юристом, стал писателем.

Details:

Был + nominative (e.g. был юрист) is possible, especially in more formal or stylistic contexts, and it tends to stress a fixed identity (“he was a lawyer (by identity)”), but it’s less neutral than instrumental.
Стать + nominative (e.g. стал писатель) is felt as incorrect or very old-fashioned in modern standard Russian. After стать the instrumental is strongly preferred:
- ✅ стал писателем
- ❌ стал писатель (avoid)

So in everyday modern Russian, the safe, natural forms are:

раньше был юристом
потом стал писателем

What is the difference between автор and писатель in this sentence? Aren’t they both “writer/author”?

They overlap, but they’re not exact synonyms.

писатель = writer as a profession or type of person – someone who writes literary works (novels, stories, etc.).
автор = author of a specific work (book, article, song, law, idea, etc.), not necessarily a professional writer.

In this sentence:

Этот автор – “this author” (of some work we are talking about now),
стал писателем – he later became a writer by profession.

So the idea is: the person we know as the author of some work used to be a lawyer but later changed profession and became a writer.

Why do we show быть in the past (был) but often not in the present, e.g. Этот автор — юрист?

In Russian:

In the present tense, the verb быть (to be) is usually not used in simple statements:
- Он юрист. – He is a lawyer.
- Optionally you can add a dash: Он — юрист.
In the past and future, you normally must use быть:
- Он был юристом. – He was a lawyer.
- Он будет юристом. – He will be a lawyer.

So in your sentence:

раньше был юристом – you have to show the past tense with был.
If it were present: Этот автор (сейчас) юрист. – no есть.

What exactly does раньше mean here? Is it the same as English “used to”?

Раньше is an adverb meaning “earlier / before / previously”.

In this sentence, раньше был юристом means something like:

“earlier in his life, he was a lawyer,”
which in natural English is “he used to be a lawyer.”

Russian does not have a special tense like English “used to”. Instead, it often uses:

раньше / прежде / когда-то
- past tense of an imperfective verb.

Examples:

Раньше он курил. – He used to smoke.
Она раньше жила в Москве. – She used to live in Moscow.

So раньше был юристом ≈ “he used to be a lawyer,” but literally: “earlier he was a lawyer.”

Can раньше go in a different place, like Этот автор был раньше юристом?

Yes, Russian word order is flexible, and you can move раньше, but the most neutral position here is:

Этот автор раньше был юристом…

Other options:

Раньше этот автор был юристом, но потом стал писателем.
- Emphasis on раньше / the idea of “in the past”.
Этот автор был раньше юристом, но потом стал писателем.
- Also possible; раньше is closer to был, still understandable, a bit less standard-sounding.

The meaning doesn’t radically change, but:

Placing раньше at the start or near the verb is most common.
The original word order is what you should imitate as a learner.

What does потом add here? Can we just say …но стал писателем?

You can say:

Этот автор раньше был юристом, но стал писателем.

This is grammatically correct. It means:

“This author used to be a lawyer, but (he) became a writer.”

Adding потом explicitly marks the time sequence: first he was a lawyer, then he became a writer.

но стал писателем – “but became a writer” (contrast + change)
но потом стал писателем – “but then became a writer” (contrast + change afterwards)

So потом makes the timeline clearer: “but later / afterwards he became a writer.”

Why do we use стал here? What is the difference between стал писателем and был писателем?

стал писателем = “became a writer”, emphasizes a change of state / profession.
был писателем = “was a writer (at some time)”, just describes a state in the past.

In this sentence we want a contrast and a change:

Before: был юристом – he was a lawyer.
After: стал писателем – he became a writer (changed his profession).

If we said:

Этот автор раньше был юристом, но потом был писателем.

it would sound strange, like we are just listing two past states without clearly saying that he changed from one to the other.

Could we say становился писателем instead of стал писателем?

You could, but it would mean something different and would sound odd in this simple biographical sentence.

стал писателем – perfective, result: he became a writer (we focus on the fact that he reached that state).
становился писателем – imperfective, process: he was becoming a writer, was in the process of turning into a writer, or did so repeatedly.

Examples where становиться makes sense:

Он постепенно становился писателем. – He was gradually becoming a writer.
В его воображении он много раз становился писателем. – In his imagination, he became a writer many times.

In your sentence, we just need the simple fact of change, so стал писателем is exactly right.

Why is there a comma before но?

In Russian, you normally put a comma before the conjunction но when it connects two clauses (two parts with their own verb).

Here we have two clauses:

Этот автор раньше был юристом – clause 1 (subject + verb).
(он) потом стал писателем – clause 2 (subject is understood, verb is стал).

They are joined by но:

Этот автор раньше был юристом, но потом стал писателем.

Because these are two independent (or semi-independent) statements in contrast, a comma is required before но by standard punctuation rules.

How would the sentence change if we are talking about a woman instead of a man?

There are two issues: verb gender and noun gender.

Verb gender in the past:
- Masculine: был, стал
- Feminine: была, стала

So for a woman, you must say:

Эта … раньше была юристом, но потом стала писателем.

Nouns for professions:

In modern Russian, many profession titles stay grammatically masculine, even for women, especially in formal speech:

Она была юристом. – She was a lawyer.
Она стала писателем. – She became a writer.

You can also use feminine forms (some are more colloquial or stylistically marked):

писательница – female writer
юристка – female lawyer (used, but can sound less formal)

So possible versions:

Эта писательница раньше была юристом, но потом стала писательницей.
Эта автор раньше была юристом, но потом стала писателем.

Using masculine profession nouns with feminine verbs (она была юристом, стала писателем) is completely normal and very common.

How do you pronounce and stress автор, юристом, писателем, раньше, стал?

Here is the stress (marked with ´) and a rough English-style pronunciation:

а́втор – [ÁV-tar]
- Stress on the first syllable.
юри́стом – [yoo-REEST-əm]
- Stress on -рист-: юри́стом.
писа́телем – [pee-SAH-tye-lyem]
- Stress on -са́-: писа́телем.
ра́ньше – [RAN’-she]
- Stress on the first syllable: ра́ньше.
ста́л – [STAL] (like “stull” but with clear a as in “father”)
- Stress on the only syllable: ста́л.

Remember: in Russian, only one syllable in a word is stressed, and that stress is very important for correct pronunciation and understanding.