A: With good posture, a firm handshake, and direct eye contact.
You assumed I'd be scrutinizing your clothes for designer labels, right? Wrong. While it's fine to wear recognizably high-end items (it shows taste and fashion savvy), it's hardly required. You can do something simple and inexpensive—a black turtleneck or white shirt with black trousers—if you score high on my personal "big three":
1. A good haircut—you'll look better, smarter, sharper.
2. A great watch—a men's style is the safest bet (no gems, no gimmicks).
3. Stylish shoes—not necessarily expensive but well cared for and sleek.
And that's it. You don't want to overaccessorize. I once interviewed a woman who showed up wearing a man's tie under a button-front shirt! Horrendous. Another applicant had on huge, dangly earrings that resembled napkin rings. When in doubt, think classic.