Мы часто советуемся друг с другом, когда планируем поездку.

Because советоваться means to consult with someone / to discuss together, while советовать usually means to advise.

So:

• Мы советуем = We advise
• Мы советуемся = We consult with each other / We discuss things together

The -ся changes the meaning. In this sentence, the idea is not that we give advice, but that we ask each other for advice and discuss things together, so советуемся is the correct form.

Друг с другом means with each other or with one another.

It is a very common Russian expression used to show mutual action between two or more people.

Examples:

• Они разговаривают друг с другом = They talk to each other
• Мы часто спорим друг с другом = We often argue with each other

In your sentence, it makes the mutual meaning explicit: we consult with each other.

Because the form depends on the preposition and the case required by the verb or expression.

• друг друга is often used without a preposition, especially as a direct object:
  • Мы знаем друг друга = We know each other
• друг с другом is used with the preposition с when the idea is with each other:
  • Мы советуемся друг с другом
  • Мы говорим друг с другом

Here, the verb structure is basically советоваться с кем? = to consult with whom?
So Russian uses с + instrumental, which gives с другом in this expression.

Because the preposition с in the meaning with normally takes the instrumental case.

So:

• с братом = with a brother
• с подругой = with a female friend
• с другом = with a friend

In the set expression друг с другом, the second word changes according to that rule: с другом is instrumental.

Russian often leaves out the subject when it is already clear from the verb ending.

So:

• Мы часто советуемся друг с другом, когда планируем поездку.
• Literally: We often consult each other, when [we] plan a trip.

The verb планируем already shows we, so repeating мы is unnecessary.

You could say:

• ..., когда мы планируем поездку

and that is also correct, but omitting мы sounds natural and efficient.

Because the sentence describes a habitual action: something that often happens in general.

• Мы часто советуемся друг с другом, когда планируем поездку. = We often consult each other when we plan a trip.

This is not about one specific future trip. It means whenever we are planning a trip, we often discuss it together.

Russian commonly uses the present tense for repeated or general situations like this.

Because поездку is the accusative singular form of поездка.

The verb планировать takes a direct object:

• планировать что? = to plan what?

So:

• планировать поездку = to plan a trip

Since поездка is a feminine noun, its accusative singular is поездку.

Usually, yes. Поездка is a general word for trip, journey, or outing, especially a specific instance of travel.

It can be used for many kinds of trips:

• a business trip
• a vacation trip
• a weekend trip
• a short journey somewhere

It is a very common and flexible word.

That is a natural and common word order in Russian:

• Мы часто советуемся друг с другом...

Russian word order is more flexible than English, but this order sounds neutral and natural.

You could move часто for emphasis, for example:

• Часто мы советуемся друг с другом...
• Мы советуемся друг с другом часто...

But the original version is the most straightforward neutral choice.

Very often, yes.

A very common pattern is:

• советоваться с кем? о чём?

Examples:

• Я советуюсь с братом = I consult my brother / I consult with my brother
• Мы советовались с друзьями о поездке = We consulted with friends about the trip

In your sentence, the с кем? part is expressed with друг с другом.

No. That would sound strange in English and does not reflect how Russian works here.

Even though -ся can sometimes look like oneself, in this sentence советуемся does not mean advise ourselves. It means consult, take counsel, or discuss together.

So the natural sense is:

• We often consult with each other when planning a trip
• We often discuss things with each other when we plan a trip

Both are good ways to understand it.

Russian uses a full finite verb:

• когда планируем поездку = literally when [we] plan a trip

But in natural English, this may also be rendered as:

• when planning a trip

depending on style.

So for understanding the grammar, think when we plan a trip. For smooth English translation, when planning a trip can also work.

Sometimes yes, but друг с другом adds clarity and emphasis.

• Мы часто советуемся, когда планируем поездку. = We often consult [someone / each other] when planning a trip.

This could still be understood, but it is a little less explicit.
Adding друг с другом makes it completely clear that the action is mutual between the people in мы.

So the full sentence sounds very natural and clear.