Dress good to always give yourself confidence.There is a psychological effect when you do that. Your body responds to your thoughts and that influences how you feel. How you feel projects how you look!
Haven't you had days when you wore something great and bumped into some people you like? You were so glad that it happened. There are also days when you accidentally had a chance meeting with your boss looking like a total slob? You didn't feel very good then did you?
When you feel confident, great, and on top of the world, it reflects a certain poise. You look healthy, radiant and ready to take on the world!
When you're feeling low, sloppy, ugly - you feel like bear just wanting to crawl back under to hibernate for months. You hope you don't meet anyone. That also will show up in your poise .