First some basic definitions:
Casual (where I like to live) – collared shirt, polo shirt or even T-shirt; slacks, jeans or shorts
Business Casual – typically sport coat with a tie or just a collared shirt and pants that hold a crease.
Business – suit and tie (maybe sport coat with proper slacks)
Semi-Formal – dark suit and tie (no sport coat)
Formal/Black Tie – tuxedo (if necessary dark suit and tie will suffice)
Here are 6 things we guys should keep in mind when dressing for work:
1. Shoes – you’d be surprised how many people judge us by the shoes we wear. Leather shoes should be polished ... dull, scuffed, dirty, cracked are all unacceptable descriptions for the shoes you wear to work. Always wear shoes that are as dark or darker than your pants. Unless you are a lifeguard, never wear sandals to work.
2. Socks – if you are dressing business casual or above, don’t wear socks that are lighter than your pants. And don’t wear ankle-length socks with long pants that are not jeans, only mid-calf or over-the-calf are appropriate.
3. Pants – get your trousers properly hemmed. If they are too short, you look like a teen-ager going through a growth spurt or that you borrowed somebody else's clothes (make sure they touch the tops of your shoes); if they are too long, you look sloppy (and, if the back hits the floor, you’ll ruin them quickly).
4. Tie – learn to tie your tie correctly with a dimple below the knot and leave it in position (avoid loosening it and opening your collar unless you got to work at 6am and it’s now 9pm or you are in the 18th hour of a telethon). Never wear a tie with a short sleeve shirt ... I don’t care how hot it is, a tie requires a long-sleeve dress shirt.
5. Suits – never button all the buttons on your suit jacket; either leave them all open or button all but the bottom button. Avoid one-button and four button suits.
6. General Condition – if it is dirty or torn, don’t wear it. If it doesn’t fit, either have it tailored or get rid of it (or change your body). If you can’t button a sport coat or suit jacket, don’t wear it.
Now how about dressing for success? Above and beyond the tips above, the best rule of thumb is to, when appropriate, dress like your boss or dress to the position to which you aspire. If you are a salesperson, and want to be a sales manager, dress like one. If your boss tends towards blue suits, it couldn’t hurt for you to follow his lead. These last suggestions are applicable to women in the workplace as well.