Prima di uscire, controllo sempre il portafoglio e le chiavi.

Because after prima di when the subject stays the same, Italian normally uses the infinitive.

• Prima di uscire = before leaving / before I leave
• uscire is the infinitive: to go out / to leave

So the structure is:

• prima di + infinitive

Examples:

• Prima di mangiare, mi lavo le mani. = Before eating, I wash my hands.
• Prima di dormire, leggo un po'. = Before sleeping, I read a little.

If the subject changes, Italian often uses prima che + a verb instead:

• Prima che tu esca, chiudi la finestra. = Before you leave, close the window.

Because it follows the preposition di in the expression prima di.

In Italian, after many prepositions or fixed expressions, a verb appears in the infinitive:

• prima di uscire
• dopo aver mangiato
• senza parlare

English often uses before + -ing or before + subject + verb, but Italian commonly uses:

• prima di + infinitive

So uscire here is completely normal.

Italian usually does not need the subject pronoun unless it is needed for emphasis, contrast, or clarity.

• controllo already means I check
• The ending -o shows it is first person singular

So:

• controllo = I check
• io controllo = I check / I check, with extra emphasis

Italian often leaves out pronouns where English must include them.

Examples:

• Mangio adesso. = I’m eating now.
• Andiamo. = We’re going.

You could say io controllo if you wanted contrast:

• Tu esci subito, io controllo prima il portafoglio.

It can mean either, depending on context.

The Italian present tense often covers both:

• I check
• I am checking
• sometimes even I do check

In this sentence, sempre makes it clear that this is a habitual action:

• controllo sempre = I always check

So here the natural meaning is the simple present:

• I always check my wallet and keys

That is a very natural position for sempre in Italian.

• controllo sempre il portafoglio e le chiavi

Italian adverbs often come:

• after the verb
• or in other positions for emphasis

This sentence sounds neutral and natural.
You may also hear:

• Prima di uscire, sempre controllo il portafoglio e le chiavi — possible, but less neutral and more marked
• Controllo il portafoglio e le chiavi sempre — possible in some contexts, but less natural here

So controllo sempre is the best basic pattern to learn.

Italian uses definite articles much more often than English with everyday objects, body parts, clothing, and things understood from context.

So:

• il portafoglio
• le chiavi

sounds natural even though English might prefer:

• my wallet and keys
• the wallet and the keys
• or just wallet and keys, depending on context

In Italian, if it is obvious whose things they are, the possessive is often unnecessary.

Compare:

• Ho preso le chiavi. = I took the keys / my keys.
• Mi lavo le mani. = I wash my hands.

So the articles here are normal and idiomatic.

Because chiave is a feminine noun.

Its forms are:

• la chiave = the key
• le chiavi = the keys

So:

• singular: la chiave
• plural: le chiavi

This is one of those nouns where the singular ends in -e and the plural changes to -i, but the gender stays feminine.

Because portafoglio is a masculine singular noun.

Its forms are:

• il portafoglio = the wallet
• i portafogli = the wallets

A learner might expect something different because the word ends in -o, but that ending is actually very common for masculine singular nouns.

So:

• il matches masculine singular
• le matches feminine plural

That is why the sentence has:

• il portafoglio e le chiavi

It is not absolutely required in every context, but it is very common and helpful.

Prima di uscire is an introductory phrase, and the comma makes the sentence easier to read:

• Prima di uscire, controllo sempre il portafoglio e le chiavi.

Without the comma, the sentence is still understandable:

• Prima di uscire controllo sempre il portafoglio e le chiavi.

But the version with the comma is clearer and more standard in careful writing.

Not in that form.

If you want to use a possessive, Italian usually needs:

• the possessive adjective
• and the correct article

So you would say:

• Prima di uscire, controllo sempre il mio portafoglio e le mie chiavi.

But this sounds a bit more explicit than necessary. In everyday Italian, the original sentence is more natural:

• Prima di uscire, controllo sempre il portafoglio e le chiavi.

Because it is already obvious they are your wallet and keys.

Yes. Uscire is a flexible verb and can often be translated in different ways depending on context.

It can mean:

• to go out
• to leave
• to exit

In this sentence, English might translate it as:

• Before leaving...
• Before going out...

Both work, depending on the situation. The Italian itself is perfectly natural and broad.

Yes, in some contexts, but the nuance is slightly different.

• uscire focuses on physically going out / leaving a place
• andare via means to go away / to leave, often with a slightly broader or more conversational feel

So:

• Prima di uscire = before going out / before leaving
• Prima di andare via = before going away / before leaving

In your sentence, uscire is probably the most natural choice because checking your wallet and keys is something you typically do before going out of the house.

It describes a habit.

The key word is sempre:

• sempre = always

So the sentence means this is something the speaker regularly does before leaving.

Without sempre, the sentence could be more neutral and might depend more on context:

• Prima di uscire, controllo il portafoglio e le chiavi.

That could still describe a habit, but sempre makes the habitual meaning very clear.