Перед тем как надеть платье, лучше снять бирку.

Yes—it's best to treat перед тем как as a set expression meaning before or before doing something.

So:

Перед тем как надеть платье
= Before putting on the dress

Literally, the words have separate meanings, but for practical learning, it works like a conjunction that introduces a time clause.

You will often see it with:

• a finite verb: Перед тем как он ушёл... = Before he left...
• an infinitive, especially when the subject is understood: Перед тем как надеть платье... = Before putting on the dress...

Because Перед тем как надеть платье is the subordinate clause, and лучше снять бирку is the main clause.

When the subordinate clause comes first in Russian, it is separated from the main clause by a comma:

Перед тем как надеть платье, лучше снять бирку.

There is no comma inside перед тем как here because the clause boundary comes after the whole expression.

You may also see forms like перед тем, как in other sentence structures, especially when the main clause comes first, but in this sentence the punctuation is completely normal.

Both verbs are infinitives because the sentence is giving general advice, not describing a specific person doing the action right now.

Russian often uses this pattern:

• лучше + infinitive = it’s better to...
• перед тем как + infinitive = before doing...

So the sentence is structured more like:

Before putting on the dress, it’s better to remove the tag.

The person doing the actions is understood as a general you / one / the wearer.

This is a very common learner question.

In standard Russian:

• надеть = to put on an item of clothing
• одеть = to dress a person

So:

• надеть платье = to put on a dress
• одеть ребёнка = to dress a child

A useful rule is:

• надеть что? = put on what?
• одеть кого? = dress whom?

So надеть платье is the correct standard form here.

Because the sentence refers to single, complete actions:

1. first remove the tag,
2. then put on the dress.

Perfective verbs focus on the action as a completed whole:

• надеть = to put on, successfully/on completely
• снять = to remove/take off

If you used imperfective forms like надевать or снимать, the meaning would sound more like a process, repetition, or general ongoing action.

Here the speaker means a one-time sequence, so perfective is the natural choice.

Because бирку is the accusative singular form.

The verb снять takes a direct object, and the thing being removed is бирка (tag), so it must go into the accusative:

• nominative: бирка
• accusative: бирку

This is the normal pattern for many feminine nouns ending in -а:

• книга → книгу
• лампа → лампу
• бирка → бирку

Because платье is a neuter inanimate noun, and for this kind of noun, the accusative singular is the same as the nominative singular.

So:

• nominative: платье
• accusative: платье

That is why after надеть you still see платье, even though it is the direct object.

Here лучше means it’s better or you’d better, and it forms an impersonal recommendation.

So:

лучше снять бирку
= it’s better to remove the tag
= you’d better remove the tag

There is no explicit subject, but Russian often leaves it out in this kind of general advice.

Compare:

• Лучше подождать. = It’s better to wait.
• Тебе лучше подождать. = You’d better wait.

In your sentence, the shorter impersonal version is used.

It could, but it does not have to.

Russian often leaves out information that is obvious from context. Since the sentence has just mentioned the dress, бирку is clearly understood as the tag attached to the dress.

So:

• снять бирку = remove the tag
• снять бирку с платья = remove the tag from the dress

The longer version is more explicit, but the shorter version is completely natural here.

Yes. Russian word order is flexible.

For example, this is also natural:

Лучше снять бирку перед тем как надеть платье.

The meaning stays basically the same: it is better to remove the tag before putting on the dress.

The version with the time phrase first—

Перед тем как надеть платье, лучше снять бирку.

—puts a bit more focus on the timing: before putting it on...

So the change is mostly about emphasis and information flow, not grammar.

The subject is not stated explicitly, but it is understood as a general person—basically you, one, or the person wearing the dress.

That same understood subject applies to both actions:

• надеть платье = to put on the dress
• снять бирку = to remove the tag

So the sentence means something like:

Before you put on the dress, it’s better to remove the tag.

Russian often omits the subject when giving general instructions or advice like this.