Antes de salir, tengo que atar bien los cordones de las zapatillas.

Because antes needs de before an infinitive.

• antes de + infinitive = before doing something
• So antes de salir = before going out / before leaving

This is a very common pattern in Spanish:

• antes de comer = before eating
• antes de dormir = before sleeping
• antes de entrar = before entering

If you use a full conjugated verb instead, then you normally use antes de que:

• Antes de que salgas... = Before you go out...

So in your sentence, antes de salir is the correct structure.

Tengo que + infinitive means I have to + verb.

So:

• tengo que atar = I have to tie

It is one of the most common ways to express obligation in everyday Spanish.

You could also say:

• debo atar... = I must / I ought to tie...

But tengo que is often more natural and common in everyday speech.

Atar means to tie.

It is the normal verb for tying things such as:

• atar los cordones = tie the shoelaces
• atar una cuerda = tie a rope
• atar una bolsa = tie a bag

With shoelaces, atar is exactly the natural verb you would expect.

Depending on region, you may also hear amarrar, but atar is standard and very common.

Bien is an adverb here, meaning something like:

• well
• properly
• securely

So atar bien los cordones means not just to tie the laces, but to tie them properly / securely.

This often sounds more natural in Spanish than translating well literally in every situation. Here it suggests the laces should be tied firmly enough so they do not come undone.

Spanish often uses definite articles where English uses possessives.

So instead of saying:

• mis cordones
• mis zapatillas

Spanish very often says:

• los cordones
• las zapatillas

when it is already clear whose they are.

That is why atar bien los cordones de las zapatillas sounds natural, even though English would often say tie my shoelaces.

This is very common with clothes, body parts, and personal items:

• Me lavé las manos = I washed my hands
• Me puse la chaqueta = I put on my jacket

Each noun needs its own article here:

• los cordones = the laces
• las zapatillas = the trainers / sneakers

And de links them:

• los cordones de las zapatillas = the laces of the trainers

So the structure is very literal in Spanish:

• the laces of the trainers

Even though English usually prefers the trainers' laces or simply my shoelaces, Spanish naturally uses this noun + de + noun pattern.

In Spain, zapatillas very often means trainers / sneakers, especially in everyday speech.

So:

• las zapatillas = sneakers / trainers

However, this word can vary a lot by region. In some Spanish-speaking countries, zapatillas may mean something more like:

• slippers
• ballet flats
• light shoes

If you want to be extra clear in Spain, you may also hear:

• zapatillas deportivas = sports shoes / trainers

In this sentence, a learner of Spain Spanish should understand zapatillas as trainers / sneakers.

Yes, you could, and it would be grammatically correct.

For example:

• Antes de salir, tengo que atar bien mis cordones.
• Antes de salir, tengo que atar bien los cordones de mis zapatillas.

But in normal Spanish, the original version sounds very natural because the owner is already obvious from the context.

Spanish often avoids possessives when they are unnecessary.

So:

• los cordones de las zapatillas = natural
• mis cordones = also possible, but slightly more explicit

It can mean either, depending on context.

Salir is a broad verb that can mean:

• to leave
• to go out
• to head out

In this sentence, antes de salir could be understood as:

• before leaving
• before going out

Both work well. The exact English choice depends on the situation.

Yes. Spanish allows some flexibility.

The original sentence:

• Antes de salir, tengo que atar bien los cordones de las zapatillas.

is very natural.

You could also say:

• Tengo que atar bien los cordones de las zapatillas antes de salir.

This means the same thing. The version with Antes de salir at the beginning puts slightly more focus on the time frame: before leaving.

Both are correct.

Because Antes de salir is an introductory phrase at the beginning of the sentence.

In Spanish, a comma is often used after this kind of opening phrase, especially in careful writing:

• Antes de salir, ...
• Después de comer, ...
• Al llegar, ...

In informal writing, some people may omit it, but using the comma here is perfectly normal and recommended.

Yes, absolutely.

A very common alternative is:

• Tengo que atarme los cordones.

This literally means I have to tie the laces to myself, but in natural Spanish it simply means I have to tie my shoelaces.

This is a common Spanish pattern with a reflexive pronoun plus an article:

• atarme los cordones = tie my shoelaces
• lavarme las manos = wash my hands
• ponerme la chaqueta = put on my jacket

So your original sentence is correct, but atarme los cordones is also very natural and often more idiomatic when talking about your own shoelaces.