There are countless books, blogs, and articles written about sales; videos have been filmed, and numerous trainings and masterclasses have been conducted. Everywhere we find advice on what makes sales effective — how to succeed in negotiations, how to achieve results, how to grow.

But this time, we want to talk about the opposite —
what to avoid in sales, or in other words, what doesn’t fly.

These are issues on which practitioners, theorists, and — most importantly — customers all agree.

Let’s look at four major mistakes that are unacceptable in the sales process:

1. Lying — the reason sales has a bad reputation
The biggest damage in sales comes from lying, which harms the customer and their interests.
Research shows that the most successful sales professionals are, first and foremost, honest and trustworthy individuals.
Premeditated lying is particularly problematic, because negotiations can shift unexpectedly — and ultimately, you might end up deceiving yourself.
That’s why honesty in sales is not just an ethical matter; it's the foundation of effectiveness.

2. Lack of preparation — a sign of unprofessionalism
Many people in sales overlook the importance of preparation.
They focus only on the negotiation itself and the final result — i.e., “closing the deal.”
However, a successful sale requires thorough preparation, including:
– researching the client
– analyzing the market and competitors
– identifying expectations and needs
Lack of preparation not only leads to ineffective negotiation, but also signals disrespect to the client.
And long-term relationships are built on respect.

3. Talking too much — overloading your audience
Everything seems to be going well in the meeting — you’re motivated, and the client appears interested.
But in the heat of the moment, you begin talking too much.
You end up repeating the same points several times, significantly reducing your effectiveness.
The client gets tired, the brain cannot retain large amounts of information, and your key message gets lost.
It’s far more effective to speak briefly and clearly about the benefits your product offers the client, rather than listing its features.
A well-placed emphasis shows that your goal isn’t just to make a sale — but to address real customer needs.

4. Post-meeting analysis
One of the most frequently missed steps in sales is reflecting after a meeting.
We rarely ask the crucial questions:
– What worked and what didn’t?
– What could we have done better?
– How can we improve next time?
Without this analysis, there is no real growth or development.
Also, people often make generous promises during negotiations — and then forget about them entirely once the process ends.
This is not only unprofessional, but it also destroys trust.
A promise unfulfilled harms both your personal reputation and your company’s image.

There are rules in sales that simply must not be broken.
These aren’t just technical mistakes — they concern human connection, professionalism, and trustworthiness.
If you want to succeed in the field of sales, always remember:
Sales isn’t just about closing a deal — it’s about building relationships.