Αν δεν βάλω αντηλιακό πριν φορέσω το μαγιό μου, καίγομαι εύκολα και πονάνε οι ώμοι μου το μεσημέρι.

Because after αν (if) and after πριν (before), Greek often uses the perfective non-past form of the verb.

So:

• βάλω = the form used for put on / apply as a single completed action
• φορέσω = the form used for put on / wear as a single action

In this sentence, the speaker means:

• if I don’t apply sunscreen
• before I put on my swimsuit

That is why Greek chooses forms that point to a single complete event, not an ongoing or habitual one.

Compare:

• Αν βάζω αντηλιακό... would sound wrong here.
• Αν βάλω αντηλιακό... = If I put on sunscreen...

The same idea applies to φορέσω.

Because after αν (if), Greek uses δεν for negation, not μη(ν).

So:

• αν δεν βάλω = if I don’t put on / apply
• not αν μην βάλω

This is an important pattern:

• Αν δεν έρθει, θα φύγουμε. = If he doesn’t come, we’ll leave.

Even though βάλω looks like a subjunctive-type form, the negative after αν is still δεν.

By contrast, μη(ν) is used with other subjunctive environments, for example:

• Να μην πας. = Don’t go.
• Πριν μην... is not used this way here.

So in this sentence, αν δεν βάλω is exactly what you want.

Because πριν can be followed directly by this verb form.

So:

• πριν φορέσω = before I put on / wear

This is a very normal and natural structure in Modern Greek.

You may also hear πριν να φορέσω, but πριν φορέσω is very common and often more straightforward.

So the structure is:

• πριν + perfective non-past verb

Examples:

• πριν φύγω = before I leave
• πριν μπω = before I go in
• πριν φορέσω το μαγιό μου = before I put on my swimsuit

Because Greek φοράω / φορώ can mean both:

• wear
• put on

The exact meaning depends a lot on the form and the context.

Here, φορέσω is a single completed action, so it is most naturally understood as:

• put on my swimsuit

If you said:

• Φοράω το μαγιό μου.

that usually means:

• I’m wearing my swimsuit.

But:

• Να φορέσω το μαγιό μου;
• Πριν φορέσω το μαγιό μου...

means:

• Should I put on my swimsuit?
• Before I put on my swimsuit...

So the aspect of the verb helps give the English sense of put on.

Because here αντηλιακό is being used in a general, non-specific way, like an uncountable substance:

• βάλω αντηλιακό = put on sunscreen

This is very natural in Greek, just as in English we often say put on sunscreen, not necessarily put on the sunscreen.

If you used the article, it would sound more specific:

• να βάλω το αντηλιακό = to put on the sunscreen
  maybe a particular sunscreen we already know about

So:

• βάλω αντηλιακό = sunscreen in general
• βάλω το αντηλιακό = a specific sunscreen

Yes. Greek commonly uses βάζω for applying many things to the body.

So βάζω can mean:

• put on
• apply

Examples:

• βάζω αντηλιακό = apply sunscreen
• βάζω κρέμα = put on / apply cream
• βάζω κραγιόν = put on lipstick

This is very normal Greek usage. Even if English prefers apply in some contexts, Greek often just uses βάζω.

Because καίγομαι means I get burned / I burn, especially in the sense of getting sunburned.

It is a middle/passive-looking form, but in Greek many verbs of this type have an everyday meaning that is not truly passive in the English sense.

So:

• καίω = I burn something
• καίγομαι = I get burned / I burn

In this sentence:

• καίγομαι εύκολα = I get burned easily

That is the natural Greek way to say it.

Because the sentence expresses a general repeated result, not one single future event.

It means something like:

• Whenever / if I don’t put on sunscreen before putting on my swimsuit, I get burned easily and my shoulders hurt at midday.

So Greek uses the present to describe something habitual or generally true for the speaker.

If the speaker were talking about one specific future situation, the wording might be different. But here the meaning is more like a personal pattern or tendency.

So:

• καίγομαι εύκολα = I get burned easily
• πονάνε οι ώμοι μου = my shoulders hurt

These are present-tense statements of repeated experience.

Because the subject is οι ώμοι μου = my shoulders, which is plural.

So the verb must also be plural:

• πονάει / πονά = it hurts
• πονάνε = they hurt

Here:

• οι ώμοι μου πονάνε
• literally: my shoulders hurt

Greek word order is flexible, so the sentence puts the verb first:

• πονάνε οι ώμοι μου

But the meaning is the same as:

• οι ώμοι μου πονάνε

Also, πονάνε is a very common spoken form. You may also see:

• πονούν

Both mean hurt here.

Because Greek usually shows possession with a weak pronoun like μου placed after the noun.

So:

• το μαγιό μου = my swimsuit
• οι ώμοι μου = my shoulders

Each possessed noun normally gets its own possessive marker.

This is different from English, where one my can sometimes cover a whole phrase more broadly. In Greek, repeating μου is natural and expected.

Also notice that Greek usually keeps the article:

• το μαγιό μου
• οι ώμοι μου

That is the normal pattern for possessives.

Because Greek normally uses the definite article + noun + possessive clitic structure.

So the usual pattern is:

• το βιβλίο μου = my book
• η μητέρα μου = my mother
• οι ώμοι μου = my shoulders

This is completely standard Greek. The article is not optional decoration here; it is part of the normal possessive structure.

So even though English says just my shoulders, Greek says literally something closer to:

• the shoulders of me

but you should think of it simply as the normal way to say my shoulders.

Greek often uses time expressions with the article and no preposition.

So:

• το πρωί = in the morning
• το βράδυ = in the evening / at night
• το μεσημέρι = at noon / around midday / in the middle of the day

That is why the sentence says:

• πονάνε οι ώμοι μου το μεσημέρι

literally:

• my shoulders hurt the midday

but naturally:

• my shoulders hurt at noon / around midday

This is a very common Greek time expression pattern.

Εύκολα means easily.

Here it modifies καίγομαι:

• καίγομαι εύκολα = I get burned easily

Its position is very natural: it comes right after the verb. Greek adverb placement is fairly flexible, but this is one of the most common positions.

You could also hear slight variations in word order for emphasis, but:

• καίγομαι εύκολα

is the standard, neutral phrasing.

Yes. Greek word order is much more flexible than English word order.

So all of these are possible, depending on emphasis:

• πονάνε οι ώμοι μου
• οι ώμοι μου πονάνε

The version in your sentence puts the verb first, which is very natural in Greek. It can sound a bit more fluid in connected speech after και:

• και πονάνε οι ώμοι μου το μεσημέρι

If you move οι ώμοι μου earlier, the meaning does not really change; the emphasis may shift slightly toward my shoulders.

So yes, the word order is flexible, but the original sentence is perfectly natural.