On a Sunday not too long ago, I met a man who swore that his advice would make me a millionaire within thirty days. Any reasonable person would be skeptical — after all, while sudden riches might make for a great movie plot, it doesn’t happen all that often in reality.

But maybe, in some stretch of the imagination, I could have been convinced to give him the benefit of the doubt. Maybe, if this enthusiastic man with his self-published book had been dressed in a crisp Armani suit and wore shoes polished to a mirror shine, I would have let some of my skepticism go and given him a few minutes of my time.

In truth, I was not convinced — because either this man hadn’t read the book he wrote or the advice in its pages was terrible. The suit he wore was riddled with holes, his shoes had seen better days, and the hem of his trousers dangled inches above his heels.

Needless to say, I politely declined to buy a copy of his book — titled How to Become a Millionaire in 30 Days — and moved on with my errands.

We all know not to judge a book by its cover, but should we judge it by its author? When it comes to professional development, those who offer advice are living examples of the benefits (or lack thereof) of taking it. It’s simple: people need to trust a leader before they can buy into his vision. Appearance can make the difference between building that assurance or breaking it — and often, they say quite a bit about you.

What message do you want to send to the world? How you dress and present yourself is the first thing people see, and serves as the silent ambassador for your personality and abilities.

Let’s take this metaphor a few steps further by looking at a few other books that you can almost certainly judge by their authors.

Book 1: How Do You Look?

Do you put effort into your presentation? Those who meet you will be able to tell right away whether you cared enough to dress well that day. You don’t need the most expensive clothes in the world or a $500 haircut to succeed — though it would be nice! — but you do need to show your audience that you respect yourself enough to dress professionally and curate an on-brand aesthetic. If you arrive at a work meeting in rumpled clothes and messy hair, the person on the other side of the table will doubt your abilities.

Book 2: Fix it Felix or Wreck it Ralph?

When you meet someone, whether it’s a potential client, business partner, VC, or friend, they will want to know one thing pretty quickly: what are you capable of?

Their assessment will encompass all the good you have the potential to do as well as the damage. The worst impression you could give potential business partner is that you’re insincere and not real; the best would be that you have the potential to be an asset to their goals.

What does this mean about your presentation? Check your body language; are you sitting up straight? Do you make eye contact and indicate that you’re fully engaged in the conversation? Or do you hunch in on yourself and habitually check your phone? The first two indicate interest and convey confidence; the last a lack reassurance.

Signal that you are a person of competence that will make their lives easier, not harder.

Book 3: I’ve Been Around The World

Where have you been, and where are you going?

You can learn a lot at a glance. A stranger might see shopping bags in your hands and know you’ve been shopping; a student might hear you speak and gain a sense of your experience and education. The small details of where you’ve been and who you are aren’t always evident – but sometimes, they don’t need to be.

In the same way, strangers and new acquaintances will get a sense of where you’re going. Common knowledge says to dress for the job you want, and from my experience, I agree. How you present yourself signals what you want out of life and others will notice whether you are in an upward trajectory or a downward spiral.

Book 4: Excuse Me, Your Personality is Showing

Personality can be conveyed in an instant; sometimes even before words are ever exchanged. What you wear, for instance, shows to some extent your interest and sensibilities. Are you quirky? Serious? Fun-loving? Active? Your appearance will organically broadcast these traits – or, you can use your attire and appearance to represent your achievement-centered mindset and play up elements of your personality that will appeal to those you wish to impress.

Book 5: A Walk-in Closet Full of Values

Your values and priorities can be read fairly easily upon first glance.

What you choose to discuss, and how, will show others what you care about. For instance, if you want to express your faith, you could wear a cross around your neck each day — but you don’t need to. So much of who we subtly shine through in our actions, appearances, and words. Most of this value-telegraphing is innate and will happen without constant reinforcement; however, it is essential to recognize and cultivate a personal “cover” that will match the message you want to send to your audience.