Learn Hardcore Croatian: Umoran sam, ali ipak učim hrvatski navečer. - I am tired, but I still study Croatian in the evening.

Croatian often drops the subject pronoun (like ja = I), because the verb ending (-m in sam) already shows the person.
Umoran sam is the most neutral and typical way to say I’m tired.
Ja sam umoran puts extra emphasis on ja (I), as in I am tired (maybe others aren’t).
Word order with biti (to be) is flexible:
- Umoran sam. – neutral, slightly emphasizing the state (umoran).
- Ja sam umoran. – emphasizes I.

So the sentence chooses the common, neutral pattern: Umoran sam...

If a woman says this sentence, does anything change?

Yes. The adjective must agree with the speaker’s gender.

A man: Umoran sam, ali ipak učim hrvatski navečer.
A woman: Umorna sam, ali ipak učim hrvatski navečer.

Umoran (masculine) → Umorna (feminine).
The verb sam stays the same; only the adjective changes.

What exactly do ali and ipak mean here, and why are both used?

ali = but (a conjunction introducing contrast).
ipak = still / nevertheless / nonetheless (an adverb emphasizing that something happens despite the previous fact).

So:

Umoran sam, ali učim hrvatski navečer.
= I am tired, but I study Croatian in the evening.
Umoran sam, ali ipak učim hrvatski navečer.
= I am tired, but I still / nevertheless study Croatian in the evening (in spite of that).

ipak strengthens the contrast: I do it anyway.

Can I just say Umoran sam, ali učim hrvatski navečer without ipak?

Yes, that sentence is perfectly correct.

Without ipak, it’s a simple contrast: I’m tired, but I study Croatian in the evening.
With ipak, you add the nuance: I’m tired, but I still / nevertheless do it (I don’t give up).

So ipak is not required grammatically; it’s there for extra emphasis and meaning.

Where can ipak go in the sentence? Is ali ipak učim... the only option?

ipak is quite flexible in position, but some positions sound more natural.

All of these are grammatical, with slightly different emphasis:

Umoran sam, ali ipak učim hrvatski navečer.
(very natural, standard)
Umoran sam, ipak učim hrvatski navečer.
(no ali; ipak alone shows contrast: I’m tired; still, I study…)
Umoran sam, ali hrvatski ipak učim navečer.
(emphasizes hrvatski as the thing you still study in the evening)
Umoran sam, ali učim ipak hrvatski navečer.
(possible, but less common; sounds a bit marked/stylistic)

The most neutral and common here is exactly what you have:
Umoran sam, ali ipak učim hrvatski navečer.

Why is it učim and not uči? How is učiti conjugated?

učim is the 1st person singular present tense of učiti (to learn / to study / to teach).

Present tense of učiti:

ja učim – I study / learn
ti učiš – you (sg.) study / learn
on/ona/ono uči – he/she/it studies / learns
mi učimo – we study / learn
vi učite – you (pl./formal) study / learn
oni/one/ona uče – they study / learn

So in I study Croatian in the evening, you must use učim, not uči.
uči would mean he/she/it studies or it could be an imperative form (study!).

In English there’s a difference between “I study” and “I am studying”. Does učim cover both?

Yes. Croatian doesn’t have a separate continuous form like English.

učim can mean:

I study Croatian (as a habit / regularly).
I am (currently) studying Croatian.

Context usually makes it clear.

If you want to talk about the result instead of the ongoing process, you switch to a perfective verb:

učiti (imperfective) – to be studying/learning, ongoing process
- Učim hrvatski. – I’m learning / I study Croatian.
naučiti (perfective) – to learn something completely, to have learned
- Naučio sam hrvatski. – I have learned Croatian (I know it now).

In your sentence, učim is the correct ongoing/habitual form.

Do I need se after učim, like učim se hrvatski?

No. In this sentence, učim se hrvatski would be incorrect.

Use:

Učim hrvatski. – I’m learning Croatian. / I study Croatian.

About učiti se:

učiti se does exist, but it’s less common and used in different structures, e.g.:
- Djeca se uče čitanju. – Children are learning (are being taught) to read.
With a direct object like hrvatski, standard usage is simply učiti + objekt:
- učim hrvatski, učim matematiku, učim povijest.

So in your sentence, učim hrvatski is exactly right.

Why is hrvatski not capitalized? In English we write Croatian with a capital C.

In Croatian, names of languages and adjectives derived from nationalities are written with a lowercase letter.

Examples:

hrvatski – Croatian (language or adjective)
engleski – English
njemački – German
talijanski – Italian

They are only capitalized at the beginning of a sentence:

Hrvatski je težak. – Croatian is difficult.

So učim hrvatski with a lowercase h is the correct standard spelling.

Could I say učim hrvatski jezik instead of učim hrvatski?

Yes.

učim hrvatski
učim hrvatski jezik

Both are correct and mean I’m learning the Croatian language.

In everyday speech, people very often omit the noun jezik (language) and just say učim hrvatski. Adding jezik can sound a bit more formal or explicit, but there’s no real difference in meaning here.

What case is hrvatski in here, and why does it look like the basic dictionary form?

hrvatski here is in the accusative singular masculine case, as the direct object of učim (I study what? → Croatian).

For inanimate masculine nouns and adjectives, the accusative singular has the same form as the nominative singular. So:

Nominative: hrvatski (as in Hrvatski je težak.)
Accusative: učim hrvatski

That’s why it looks like the basic form, even though grammatically it’s accusative.

What does navečer mean exactly, and how is it different from večer or uvečer?

večer – a noun, meaning evening
- Večer je lijepa. – The evening is beautiful.
navečer – an adverb, meaning in the evening / during the evening / at night (in the evening time)
- Učim hrvatski navečer. – I study Croatian in the evening.
uvečer – also an adverb meaning basically the same as navečer; it’s correct but somewhat more regional/less common in standard everyday usage.

Other related expressions:

svake večeri – every evening
- Učim hrvatski svake večeri. – I study Croatian every evening.

In your sentence, navečer is a natural, standard way to say in the evening.

Can I change the word order in the second part, e.g. ... učim navečer hrvatski or ... navečer učim hrvatski?

Yes, Croatian word order is fairly flexible. All of these are grammatical:

... ipak učim hrvatski navečer. (neutral, very natural)
... ipak učim navečer hrvatski.
... ipak navečer učim hrvatski.

The differences are mostly in emphasis and rhythm, not in basic meaning. The most neutral and common in speech would probably be:

... učim hrvatski navečer.
or with ipak: ... ipak učim hrvatski navečer.

So your original order is a good, natural choice.

Why is there a comma before ali in Croatian?

In standard Croatian punctuation, you normally put a comma before the conjunctions:

ali (but)
nego (but rather)
jer (because)
iako (although)
and others that introduce a new clause.

So:

Umoran sam, ali ipak učim hrvatski navečer.

The comma separates the two clauses:

Umoran sam – I am tired
(ali) ipak učim hrvatski navečer – (but) I still study Croatian in the evening

Unlike English, where the comma before but can be more flexible, Croatian is stricter: here the comma is standard and expected.

How would the sentence change for “We are tired, but we still study Croatian in the evening”?

You need to change both the adjective and the verb to the 1st person plural:

Umorni smo, ali ipak učimo hrvatski navečer.

Breakdown:

Umorni – tired (masculine plural form; used for a mixed or all-male group)
smo – we are
učimo – we study / we are studying

For a group of only women, you’d say:

Umorne smo, ali ipak učimo hrvatski navečer.