Setelah ponsel saya terjatuh, saya jadi lebih hati-hati menyimpan barang di saku jaket.

Setelah means after. It introduces the earlier event:

• Setelah ponsel saya terjatuh = After my phone fell / after my phone got dropped

It does not have to come first. You could also say:

• Saya jadi lebih hati-hati menyimpan barang di saku jaket setelah ponsel saya terjatuh.

Putting setelah first is very natural when the speaker wants to give the background event before stating the result.

The comma after the first clause is also natural in writing, because the sentence starts with a time clause.

In Indonesian, possessors usually come after the noun.

• ponsel saya = my phone
• jaket saya = my jacket
• teman saya = my friend

So ponsel saya follows the normal Indonesian word order: noun + possessor.

These are related but not the same:

• jatuh = to fall
• terjatuh = to fall accidentally / to end up falling
• menjatuhkan = to drop something / cause something to fall

So:

• Ponsel saya jatuh = My phone fell
• Ponsel saya terjatuh = My phone accidentally fell / got dropped
• Saya menjatuhkan ponsel saya = I dropped my phone

In this sentence, terjatuh adds a sense of accident or unintendedness. That makes it sound very natural here.

Because the second clause needs its own subject.

• First clause: ponsel saya terjatuh → the subject is ponsel saya
• Second clause: saya jadi lebih hati-hati... → the subject is saya

Indonesian often states the subject clearly in each clause. If you remove the second saya, the sentence sounds incomplete or too elliptical for normal standard usage.

Here jadi means become or end up being.

• saya jadi lebih hati-hati = I became more careful / I ended up being more careful

That is a very common use of jadi in everyday Indonesian.

But yes, jadi can also mean so in other contexts, for example:

• Jadi, bagaimana? = So, what do you think?

A more formal alternative in your sentence would be menjadi, but jadi is more natural in everyday speech:

• saya menjadi lebih hati-hati = more formal
• saya jadi lebih hati-hati = more conversational and common

Hati-hati means careful, cautious, or watch out, depending on context.

In this sentence:

• lebih hati-hati = more careful

So:

• saya jadi lebih hati-hati = I became more careful

Even though hati literally means heart, hati-hati is a fixed expression. Learners should usually understand it as one unit meaning careful rather than trying to interpret it word by word.

Yes. Both are possible:

• lebih hati-hati
• lebih berhati-hati

The difference is mostly about style:

• hati-hati is very common and natural in everyday speech
• berhati-hati sounds a bit more formal or full

So in this sentence, jadi lebih hati-hati sounds very natural and idiomatic.

Menyimpan has a broad meaning: to keep, store, put away, or sometimes save.

In this sentence, it does not sound like formal long-term storage. It means something more like:

• keeping things in
• putting things in
• carrying things in

So lebih hati-hati menyimpan barang di saku jaket is naturally understood as:

• more careful about keeping/putting things in a jacket pocket

A very literal translation with store might sound stiff in English, even though menyimpan is correct in Indonesian.

Because di marks a location, while ke marks direction/movement toward something.

• di saku jaket = in/on the jacket pocket as a location
• ke saku jaket = to the jacket pocket as movement

Here the speaker is talking about the place where items are kept, so di is the natural choice.

If you wanted to emphasize movement into the pocket, you might say something like:

• ke dalam saku jaket = into the jacket pocket

But in this sentence, di saku jaket is the most natural wording.

Barang means thing, item, belonging, or stuff, depending on context.

In this sentence, it is best understood as a general noun:

• barang = things / items / stuff

Indonesian often does not mark singular vs. plural unless it really matters. So barang here can refer to one item or multiple items, but in English things is probably the most natural translation.

If the speaker really wanted to emphasize plurality, barang-barang would be possible, but it is not necessary here.

Because Indonesian often leaves out possession when it is already obvious from context.

Here the speaker is talking about their own experience:

• ponsel saya
• saya jadi lebih hati-hati...

So saku jaket is naturally understood as the jacket pocket relevant to the speaker, often effectively my jacket pocket in context.

Also, saku jaket is a normal noun phrase meaning jacket pocket, just like English compounds such as shirt pocket or coat pocket.

If you want to be extra explicit, you can absolutely say:

• di saku jaket saya

That would mean in my jacket pocket more explicitly.