1. Take a good look around you
What type of business or industry are you in? A corporate communicator or creative environment? What do clients expect? What do the movers and shakers dress like? Dress in the top 25% of your industry peers people at your job level.
2. Consistency
Business casual wear should only be one step down from your standard business wear. Not suits one day then jeans the next. Your Monday to Thursday look should not vary drastically on Friday.
3. Caution for women: women have a tougher time with credibility when dressed in a casual manner. This is especially true if you are younger, shorter or slighter. Stick to the more elegant end of casual attire by wearing a jacket or vest with coordinating bottoms. That will give you more presence.
4. Casual not sloppy clothes should be well pressed, clean and wrinkle free. Repair or replace clothing that is showing signs of wear. This advice becomes more important the more casual your dress is.
5. Jeans
If jeans are part of your business casual options, select dark over light, and ensure they are in good shape. (Jean wear is a major concern with employers. People make so many poor jean choices that many dress codes forbid them) No sand washing, holes or fraying.
6. Avoid anything too tight, too short, too bare
7. Appropriateness
Anything intended for the gym, the beach or a night club can make you a casual wear casualty.
8. Footwear
No flipflops, or strappy sandals. For men wear darker shades for athletic shoes.
9. Meet customer expectations
Your schedule should help you determine how to dress on any given day. If your position involves public contact, dress to generate client trust and credibility. If you are apologizing to visitors and clients about your dress, you've gone too casual.