Deberías haber mirado bien el nombre antes de abrir el paquete.

It is the Spanish way to say you should have looked or you should have checked.

The structure is:

• deberías = you should / you ought to
• haber mirado = to have looked

So together:

• deberías haber mirado = you should have looked

This is a very common structure in Spanish for talking about something that was advisable in the past, but did not happen.

More examples:

• Deberías haber llamado. = You should have called.
• Deberíamos haber salido antes. = We should have left earlier.

Both can relate to should have, but they do not feel exactly the same.

• Deberías haber mirado... sounds like advice, criticism, or hindsight: You should have looked...
• Debiste mirar... can sound more direct, firmer, or closer to you were supposed to look / you should have looked

In many everyday contexts, deberías haber + participle is the safest and most natural way to express should have done.

So in this sentence, deberías haber mirado sounds like a natural reproach or observation after the fact.

Because the sentence refers to something that should have happened before another past action.

• mirar = to look
• haber mirado = to have looked

Spanish uses haber + past participle after verbs like deber, poder, querer, etc. when referring to a completed past action.

Compare:

• Deberías mirar el nombre. = You should look at the name.
  (present/future advice)
• Deberías haber mirado el nombre. = You should have looked at the name.
  (past advice, now too late)

Because mirado is the past participle of mirar.

The pattern is:

• haber + past participle

So:

• haber mirado
• haber abierto
• haber llamado

For regular -ar verbs, the participle ends in -ado:

• mirar → mirado
• hablar → hablado

For regular -er/-ir verbs, it ends in -ido:

• abrir → abierto is actually irregular
• comer → comido
• vivir → vivido

Also, after haber, the participle does not change for gender or number.

Yes, literally bien means well, but in this sentence mirar bien is better understood as:

• look carefully
• check properly
• take a good look at

So mirado bien el nombre means something like:

• checked the name carefully
• looked properly at the name

This is very natural Spanish. It does not mean you looked at it in a morally good way or anything like that; it means you paid proper attention.

Because mirar usually takes a direct object without a in this kind of sentence.

So:

• mirar el nombre = look at the name / check the name

Spanish often uses direct objects where English uses look at.

Compare:

• Mira la pantalla. = Look at the screen.
• Miró el reloj. = He looked at the clock.

You do not say mirar al nombre here.

In context, el nombre most likely means the name written on the package, such as:

• the recipient’s name
• the sender’s name
• the label/name on it

Spanish often says el nombre where English might say:

• the name on the package
• the label
• the recipient name

So the sentence is naturally understood as: you should have checked whose name was on the package before opening it.

Because in Spanish, antes de must be followed by:

• a noun, or
• an infinitive

So:

• antes de abrir = before opening
• antes de salir = before leaving
• antes de comer = before eating

You cannot say antes abrir.

This is a very important pattern:

• después de + infinitive
• antes de + infinitive

Because antes de abrir el paquete is the normal and natural way to say before opening the package.

Spanish usually uses antes de + infinitive when talking about an action in general sequence.

So:

• antes de abrir el paquete = before opening the package

You could build more complex forms in some contexts, but here abrir is exactly what Spanish normally uses.

Because Spanish often leaves out subject pronouns when they are not needed.

The verb form deberías already tells you the subject is tú.

So:

• Deberías haber mirado...
• Tú deberías haber mirado...

Both are possible, but the version without tú is more neutral and more natural in many contexts.

Spanish usually adds the pronoun only for:

• emphasis
• contrast
• clarification

For example:

• Tú deberías haber mirado el nombre, no yo.

Because Spanish often uses the definite article (el, la, los, las) in places where English might use:

• the
• your
• his/her
• it

Here, el paquete simply means the package, understood from context.

If the speaker wanted to emphasise possession, they could say:

• tu paquete = your package
• su paquete = his/her/their package

But el paquete is perfectly natural when everyone already knows which package is being discussed.

Not naturally in this sentence.

• mirar = to look at
• ver = to see

Here the idea is not merely that you physically saw the name, but that you checked it deliberately. That is why mirar is the better verb.

Compare:

• Vi el nombre. = I saw the name.
• Miré bien el nombre. = I checked/looked carefully at the name.

So mirar fits the meaning much better.

Yes, usually it sounds like mild criticism, reproach, or hindsight.

Deberías haber... often implies:

• the person did not do something they ought to have done
• now there is a consequence or problem

So this sentence sounds like:

• You should have checked the name carefully before opening the package.

It is not just neutral information; it usually suggests the speaker thinks a mistake was made.

Yes. That is probably the most natural English translation in many contexts.

Literal breakdown:

• deberías haber mirado bien = you should have looked carefully

But in natural English, checked often sounds better than looked at here, because the meaning is about verifying the label or recipient.

So good English translations include:

• You should have checked the name carefully before opening the package.
• You should have looked carefully at the name before opening the package.

Both are correct; checked is just more idiomatic in many situations.