Перед тем как выйти из дома, лучше ещё раз застегнуть капюшон и проверить шнурки.

Перед тем как means before when it introduces an action, especially something like before doing X or before X happens.

In this sentence, перед тем как выйти из дома = before leaving the house / before you go out of the house.

It is built from:

• перед = before
• тем = that (in a form required by перед)
• как = how / when

As a whole, it functions like a fixed expression. Russian often uses this kind of longer connector before a clause with a verb.

You can think of it as:

• перед тем как + infinitive/clause = before doing...

There are often shorter alternatives in Russian, but перед тем как is very common and natural.

Because перед requires the instrumental case, and тем is the instrumental singular form of тот.

So:

• nominative: то
• instrumental: тем

In перед тем как, the phrase is fixed, so learners usually just memorize it as a chunk. But grammatically, тем is there because of перед.

Выйти is the perfective form, and here that makes sense because the sentence refers to completing a single action: to go out / to step out of the house.

Compare:

• выходить = imperfective, process/habit/repeated action
• выйти = perfective, one completed act of going out

In this sentence, the idea is:

• before you go out of the house (this one time)

So выйти is the natural choice.

After из meaning out of / from, Russian uses the genitive case.

So:

• дом = house, home
• из дома = out of the house / from home

Here дома is the genitive singular form of дом.

This is very common:

• из школы = out of school
• из комнаты = out of the room
• из дома = out of the house

Russian often leaves the subject unstated when it is general, obvious, or not important.

Here the sentence gives general advice:

• It’s better to fasten your hood and check your shoelaces one more time before leaving home.

So the subject is understood as a general you. English often does something similar:

• Before leaving the house, it’s better to check...

Russian does this even more freely than English.

Yes, лучше literally means better, but in this kind of sentence it works like a recommendation:

• лучше застегнуть... = it’s better to fasten...
• more naturally in English: you’d better fasten... or it’s best to fasten...

So this is not comparing two things in a strict way. It is giving practical advice.

Because they depend on лучше in an impersonal recommendation structure.

Pattern:

• лучше + infinitive

Examples:

• Лучше подождать. = It’s better to wait.
• Лучше проверить. = It’s better to check.

So in your sentence:

• лучше ещё раз застегнуть капюшон и проверить шнурки

Both verbs stay in the infinitive because they are the actions being recommended.

They are perfective because the speaker means single completed actions:

• fasten the hood
• check the shoelaces

This fits the situation well: before going out, you do these actions once and finish them.

Compare:

• застёгивать = to be fastening / to fasten repeatedly
• застегнуть = to fasten completely, once
• проверять = to be checking / check repeatedly
• проверить = to check once, completely

In advice about one specific moment, perfective infinitives are very common.

Ещё раз means one more time or again.

So:

• лучше ещё раз застегнуть капюшон = it’s better to fasten the hood one more time / again
• проверить шнурки is also understood as part of the same recommendation before leaving

In Russian, ещё раз often adds the idea of just to be safe, once more.

Grammatically, it is attached most directly to застегнуть:

• лучше ещё раз застегнуть капюшон и проверить шнурки

So the most literal reading is:

• better to fasten the hood once more and check the shoelaces

In real usage, the general feeling of do a final check before going out can color the whole phrase, but strictly speaking ещё раз is placed with застегнуть.

If someone wanted to make it clearly apply to both verbs, they could rephrase the sentence.

Yes, Russian can say застегнуть капюшон, though the exact image depends on the clothing.

It means something like:

• fasten/secure the hood
• do up the hood
• possibly zip/button it up around the neck or face area

Russian often uses the verb застегнуть with clothing parts or things that have a fastening. So even if English might phrase it differently, the Russian collocation is understandable and natural in context.

Шнурки means shoelaces.

Singular:

• шнурок = a lace, cord

Plural:

• шнурки = laces, usually shoelaces in everyday context

So проверить шнурки means:

• check your shoelaces
• in context, probably make sure they’re tied properly

It is in the accusative plural because it is the direct object of проверить.

For many inanimate plural nouns, the accusative looks the same as the nominative:

• nominative plural: шнурки
• accusative plural: шнурки

So:

• проверить что? → шнурки

Because перед тем как выйти из дома is a subordinate clause-like time expression placed before the main part of the sentence.

So the structure is:

• Перед тем как выйти из дома, = before leaving the house
• лучше ещё раз застегнуть капюшон и проверить шнурки. = it’s better to fasten the hood again and check the shoelaces

Russian separates that opening dependent part from the main clause with a comma.

No. Even though как often means how, in перед тем как you should not translate the words one by one.

As a full expression, перед тем как simply means:

• before
• before doing...
• before you...

This is a good example of why it is better to learn some Russian connectors as whole phrases rather than trying to translate each word separately.

Yes. Russian could also use a noun-based structure, for example:

• Перед выходом из дома лучше ещё раз застегнуть капюшон и проверить шнурки.

That means essentially the same thing:

• Before leaving the house, it’s better to fasten the hood again and check your shoelaces.

So:

• перед тем как выйти из дома = clause-style
• перед выходом из дома = noun-style

Both are natural. The version in your sentence is slightly more verbal and explicit.