I was training someone recently for a sales position. They came with me to several appointments and observed. At the outset of the day, he asked me, "do you always wear a suit?" I told him that I like to, yes. He said that other people he has observed only wore business casual attire and, he himself was planning to do that because he didn't want to intimidate the customer, he wanted them to feel "comfortable with him." I was astounded by this reply. The last thing we are trying to do is instill comfort, we aren't in the business of making friends. We are in the business of getting our customers to take a real, hard look at their business and recognize that which makes them the MOST uncomfortable.... they need help. They need consultation.
I told him to close his eyes and picture the most successful business consultant he could imagine. Someone that commands attention, inspires trust and looks like integrity embodied. Is he/she wearing a golf shirt and khakis?
After watching me that day, he showed up the next day in a suit and tie.
Dress the part.
Excellence is a habit.
What do you wear to job applications? On the one hand, you want to make the best first impression, on the other hand, I usually wear business casual so it represents me better. I got myself a nice navy blue suit a while ago which I use for formalities like that, but I'm more comfortable / more myself in business casual. There's also the risk of overdressing.