Learn Hardcore Croatian: Ujutro polako ustajem iz kreveta i još nisam potpuno budan. - In the morning I slowly get out of bed and I am not fully awake yet.

sounds archaic, poetic, or very unusual in modern everyday speech
would usually refer to a specific morning (into the morning of that day), and people almost never say it that way now

So for normal speech about your routine, always use ujutro.

Do I need to say ja (I)? Could I say Ujutro ja polako ustajem…?

You don’t need ja here. Croatian is a “pro-drop” language: the subject pronoun is usually omitted because the verb ending already shows the person.

Ujutro polako ustajem… – the -em ending on ustajem already tells us it’s I.
Ja ujutro polako ustajem… – also correct, but adds emphasis on I (e.g. contrasting with others).

Use ja when you want to stress I specifically:

Ja ujutro polako ustajem, ali ti ustaješ rano.
I get up slowly in the morning, but you get up early.

Why is it ustajem and not ustanem? What’s the difference?

Both come from the same verb pair, but they differ in aspect:

ustajati – imperfective (ongoing / repeated action)
- 1st person singular: ustajem
ustati – perfective (single, completed action)
- 1st person singular “present” form: ustanem (but this mostly refers to the future)

So:

Ujutro polako ustajem.
→ Describes a habit: this is what I (usually) do in the morning.
Ustanem sutra u šest.
→ “I’ll get up at six tomorrow” – a single, completed event, often future-like.

In short:
For routines / habits, use ustajem.
For one specific act of getting up (often in the future), use ustanem.

Why isn’t there a se after ustajem? I often see verbs like dižem se.

In standard Croatian, ustajati / ustati is not reflexive; you say:

Ustajem u sedam. – I get up at seven.
Ustat ću u šest. – I will get up at six.

There is another common verb for “get up”:

dizati se / dići se – literally “to raise oneself, to get up”
- Dižem se u sedam. – I get up at seven.

So:

ustajem – correct, non‑reflexive
dižem se – correct, reflexive, same meaning in this context

You may hear ustajem se in colloquial speech, but ustajem (without se) is the standard form.

Why is it iz kreveta and not od kreveta or s kreveta? And why kreveta, not krevet?

Two things are going on: the preposition and the case.

Preposition choice

iz = out of / from the inside of
→ used when you’re leaving an enclosed or “inside” space:
- iz kuće – out of the house
- iz auta – out of the car
- iz kreveta – out of bed (thought of as something you’re in)
s(a) = off (a surface) / from the top of
- sa stola – off the table
- s krova – from the roof
  You could say sići s kreveta (“get down from the bed” – from the surface), but the usual phrase for “get out of bed” is ustati / ustajati iz kreveta.
od = from (a person, origin, cause, distance, etc.)
- od prijatelja – from a friend
- daleko od kuće – far from home
  This wouldn’t be used for physically getting out of bed.

Case on krevet

iz always takes the genitive case, so:

nominative: krevet
genitive singular: kreveta

That’s why it’s iz kreveta, not iz krevet.

What tense is ustajem, and how would I say “I got up” or “I will get up”?

Ustajem is present tense, imperfective aspect, used for habits:

Ujutro polako ustajem. – I slowly get up (in the morning, as a routine).

For past (“I got up”) using ustati (perfective):

masculine speaker: Ustao sam iz kreveta.
feminine speaker: Ustala sam iz kreveta.

For future (“I will get up”):

Ustat ću u šest. – I’ll get up at six.
Ustanem sutra u šest. – Commonly also used with a future meaning.

So:

ustajem – (I) get up (regularly, in general)
ustao sam / ustala sam – I got up
uplat ću / ustanem – I will get up

Why is the word order Ujutro polako ustajem iz kreveta? Can I move the words around?

Croatian word order is flexible, but there are default preferences. A common neutral sequence for adverbs is:

Time – Manner – Place/Direction – Verb (or Verb – Place/Direction)

In your sentence:

Ujutro – time
polako – manner
ustajem iz kreveta – action + direction

So Ujutro polako ustajem iz kreveta sounds very natural and neutral.

You can move things:

Polako ujutro ustajem iz kreveta. – puts a bit more emphasis on polako.
Ujutro ustajem polako iz kreveta. – still correct, a bit marked in rhythm.
Iz kreveta ujutro polako ustajem. – grammatically okay, but starts sounding more stylistic / poetic.

For a learner, Ujutro polako ustajem iz kreveta is a very good model: Time – Manner – Verb – Direction.

What does još mean here, and is there a difference between još nisam and nisam još?

Here još means “still / yet”:

još nisam potpuno budan – I’m still not completely awake / I’m not yet completely awake.

Both još nisam and nisam još are grammatically correct:

još nisam potpuno budan – very usual, fairly neutral.
nisam još potpuno budan – also okay, sometimes a tiny nuance of focusing on “not yet (at this point)”.

In many contexts they’re interchangeable. For everyday use, još nisam potpuno budan is a very natural choice.

(Elsewhere, još can also mean “more / another”, e.g. još kave – more coffee.)

What is budan exactly? Why not a verb form like budim?

Budan is an adjective meaning “awake”.

So nisam potpuno budan literally means “I am not completely awake”.

budan – awake (masculine, singular)
budna – awake (feminine, singular)
budni / budne – awake (plural forms)

Budim is a verb form:

buditi – to wake (someone) / to wake up (imperfective)
- budim – I wake (up) / I am waking (up)

Examples:

Budim brata svaki dan. – I wake my brother every day.
Rano se budim. – I wake up early.

In your sentence you’re describing your state, not the action of waking up, so you use the adjective:

nisam potpuno budan – I’m not completely awake.

If a woman is speaking, does budan change?

Yes. Adjectives in Croatian agree with the gender and number of the subject.

A male speaker:
Ujutro polako ustajem iz kreveta i još nisam potpuno budan.
A female speaker:
Ujutro polako ustajem iz kreveta i još nisam potpuno budna.

Only budan → budna changes here.
(The verb ustajem stays the same for both genders in the present tense.)

Is potpuno necessary? What does it do, and are there synonyms?

Potpuno is an adverb meaning “completely / totally / fully”. It modifies budan:

nisam budan – I’m not awake.
nisam potpuno budan – I’m not completely awake / I’m not fully awake.

It’s not grammatically necessary; it just gives more nuance.

Common synonyms you could use in the same position:

sasvim – još nisam sasvim budan
skroz (more colloquial) – još nisam skroz budan
posve – još nisam posve budan

All these adverbs normally come before the adjective:

još nisam potpuno/sasvim/skroz budan.

Could I leave out the second part and just say Ujutro polako ustajem iz kreveta?

Yes, absolutely.

Ujutro polako ustajem iz kreveta.
– In the morning I slowly get out of bed.

This is a complete, perfectly natural sentence on its own.

In the original, i još nisam potpuno budan (“and I’m still not completely awake”) is just an extra clause joined by i (“and”), giving more information about your state after getting up. You can include it or omit it depending on what you want to say.

Are there other common sentences that follow the same pattern as Ujutro polako ustajem iz kreveta…?

Yes, the pattern [Time] + [Manner] + [Verb] + [Place/Direction] is very common. For example:

Ujutro obično pijem kavu.
In the morning I usually drink coffee.
Ujutro često kasnim na posao.
In the morning I’m often late for work.
Navečer polako idem kući.
In the evening I slowly go home.
Poslije posla uvijek sjednem na kauč.
After work I always sit down on the couch.

Your sentence fits exactly the same style: Ujutro (time) + polako (manner) + ustajem (verb) + iz kreveta (direction).