Kad sam umorna, najprije gledam veznik i glagol, a tek onda pokušavam odrediti padež i zamjenicu.

Sam is the 1st person singular present form of biti (to be), and in Croatian it behaves like a clitic. Clitics usually go in the second position of their clause.

So in Kad sam umorna:

• Kad = first element
• sam = clitic in second position
• umorna = the predicate adjective

That is why Kad sam umorna sounds natural, while Kad umorna sam does not.

Croatian adjectives must agree with the person or noun they describe in gender, number, and case.

Here, the speaker is saying I am tired, so the adjective matches the speaker:

• umorna = feminine singular
• umoran = masculine singular

So:

• a woman says Kad sam umorna
• a man says Kad sam umoran

Croatian often leaves out subject pronouns because the verb form already shows who the subject is.

Here, sam already tells us the subject is I.

So the normal sentence is:

• Kad sam umorna...

You would add ja only for emphasis or contrast, for example:

• Kad sam ja umorna, ne mogu raditi.
  = When I am tired, I can’t work.

Also, Kad ja sam umorna is not the normal word order.

Both mean when.

The difference is mostly one of style:

• kad = more common in everyday speech
• kada = a bit more formal or emphatic

In this sentence, kad is perfectly natural.

There are two reasons:

1. Kad sam umorna is a subordinate clause placed before the main clause, so it is followed by a comma.
2. The comma before a separates two coordinated parts of the sentence.

So the structure is:

• Kad sam umorna, = introductory subordinate clause
• najprije gledam veznik i glagol,
• a tek onda pokušavam odrediti padež i zamjenicu.

These words organize the sequence of actions.

• najprije = first, first of all
• onda = then
• tek onda = only then, not until then

So the sentence does not just say first... then... It says:

• first I look at the conjunction and the verb,
• and only then do I try to determine the case and pronoun.

The word tek adds emphasis: the second step comes only after the first one.

Both a and i can connect parts of a sentence, but they do different jobs.

• i = and, simple addition
• a = often and/but, with a sense of contrast, shift, or step-by-step progression

Here a tek onda works well because it marks a transition to the next stage:

• najprije ... = first
• a tek onda ... = and only then

So a helps show the contrast between step 1 and step 2.

The sentence describes a usual method or habit, not just one event happening right now.

Croatian uses the present tense for this kind of general statement, just as English does in sentences like:

• When I’m tired, I first look at...

So:

• gledam = I look
• pokušavam = I try

These forms show what the speaker typically does in that situation.

After verbs like pokušavati / pokušati (to try), Croatian very often uses an infinitive.

So:

• pokušavam odrediti = I am trying to determine

This is a very common pattern:

• pokušavam razumjeti = I am trying to understand
• pokušavam naći = I am trying to find

So odrediti is not finite here; it is the action that the speaker is trying to do.

They are all direct objects, so they are in the accusative.

Here is what is happening:

• gledam veznik i glagol
• pokušavam odrediti padež i zamjenicu

Now the forms:

• veznik → accusative singular masculine inanimate
• glagol → accusative singular masculine inanimate
• padež → accusative singular masculine inanimate
• zamjenica → zamjenicu in accusative singular feminine

A useful point for learners:

For many masculine inanimate nouns, the accusative singular looks the same as the nominative singular. That is why:

• nominative: veznik
• accusative: veznik

But feminine nouns often change, which is why:

• nominative: zamjenica
• accusative: zamjenicu

This is about aspect, which is very important in Croatian.

• gledam is imperfective: ongoing or repeated action
• pokušavam is imperfective: ongoing/repeated trying
• odrediti is perfective: to determine something successfully, as a complete act

So the idea is:

• first, I am looking
• then I am trying
• and what I am trying to do is reach a result: determine the case and pronoun

Using odrediti makes sense because the goal is a completed outcome.