We all want to make a great first impression: on friends, at work, on a date or interviewing for a new job. But a variety of factors can trigger your self-consciousness or fear, which translates in your face, your voice, and your ability to behave authentically.

I learned a surprising lesson about making a first impression in an unlikely place—beauty school, where I enrolled to become an esthetician in my 20s on my circuitous career path. I have never felt less beautiful, confident, or less like myself than during the rigors of that training. Five days a week, I awoke at 5am and spent six hours a day in white uniforms that were unflattering on every body type. Trapped all day under fluorescent lights with a group of women who regressed to high school levels of name calling and snap judgments, I felt like I was in a low-security women’s prison.

There, we sized each other up in the first moments we met; you could feel the tension in the room as groups of us paired off according to some silent call only we could hear.

Alex Todorov, a psychologist at Princeton University has done research on how people respond intuitively to faces more quickly than our rational brains can jump in to intervene. This habit, called “thin slicing” is a hardwired response grounded in the amygdala of our brains—the center of the fight or flight response, which scans for safety. Are we forever subject to our own and others’ primal reactions to the arbitrary shape of a face? Fortunately, there are other factors that go into a first impression, such as authenticity and tone of voice.

The only way I survived beauty boot camp was thanks to a call-it-like-you-see-it colleague named Shari. Shari made an impression, not the least because she was six feet tall with a long mane of blonde hair and a gunshot laugh, but I quickly noticed that everybody liked Shari. I tried to figure out why she could cut across the cliques that had formed early on. Was it because she said exactly what she thought but in a friendly way—never out to hurt your feelings or to be self-righteous? She might laugh if you stuck yourself to the person you were supposed to be waxing, but offer to take over for you.

She was unapologetically herself—saying whatever came to her mind. In a word, Shari was authentic. Social scientist and author Brene Brown writes that authenticity is a powerfully attractive force. “Authenticity is actually a collection of choices…that we make every day. It’s the choice to show up and be real. The choice to be honest. The choice to let our true selves be seen.”

Shari became my mascot when I left the beauty world—to which I was badly suited. I then got an MFA in creative writing and literature, and began to teach writing workshops. I tried not to “put on airs” or sound smarter than I was. I learned that simply delivering information was not enough to make a good first impression; my delivery counted for a lot more than I realized.

This is because, after faces, our next most instinctive way to judge a person’s character is through tone of voice. According to research done by Phil McAleer, a psychologist at the University of Glasgow, we are hard-wired to prefer higher register voices—leaning toward the female—but we also respond best to voices that sound firm, certain, don’t rise into a question or warble when we talk. Plus, people respond to enthusiasm, and certainty.

I learned the truth of this through many awkward moments—a person in the back of the room shouting, “Slow down, you talk too fast,” and another student taking me aside after to suggest I should “work on sounding more confident.” The fact is: I can best channel that strong, certain sounding tone of voice when I feel prepared for the situation I’m entering, and when I have the freedom to be myself.

This doesn’t just apply to professional life. People who do not feel good about themselves communicate this in their every word and movement. Some of us can indeed “fake it till you make it,” and for some of us, building confidence may first require therapy, meditation or church.

Ultimately, the best advice for making a good first impression is to come prepared to be yourself.

To find out about Rose’s thoughts on how to live a happier life, click here