Do the clothes make the man (or woman)? Of course not, but they do make a statement and they do make a difference.
When I used to be a slob and tended to dress down, a friend told me to check out this only-slightly outdated text: John T. Molloy's New Dress for Success.
There is also one for women: How to Dress for Success.
It's better to have three good suits or three good work dresses than to have closets full of mediocre stuff. If you have business or professional ambitions, look the part. I own only three good, conservative suits, but plenty of Brooks Brothers ties and shirts for variation. Forgot, also a summer suit. I have three sports jackets for "informal Fridays" and for church, etc. A blazer and two tweeds.
I have just three pairs of expensive dress shoes for work; brown, cordovan, and black. They ought to be good for 20-30 years at least. Somebody once told me that people always check out your footwear, and it is true. I never do that, but other people do.
If you look professional, chances are that you will be treated that way. It sounds shallow, but the way a person presents himself in public, comports himself, grooms himself, speaks, his posture, all makes a huge difference in a world in which people only have time for quick takes and generally are not very interested in you because they know enough people already. After all, how you look is your decision about how you have chosen to present yourself to others. If you look like a schlub, people will assume that that is what you are or what you aspire to. If you look too natty, or whorish, conclusions will also be drawn.
We identify ourselves, introduce ourselves, before we open our mouths. Do I appraise people on their appearance? Of course I do. Everybody does. It's termed "signaling." It's not always accurate for sure, but it's a rule of thumb for people with little time.
