One's wardrobe will depend on many variables such as industry, position, climate, and culture.  For the first day "on-the-job", it is always best to select a conservative outfit.  However, once situated, you can more easily observe how your colleagues are dressed and mimic similar attire. 

Dressing to fit in with the company culture shows that you pay attention to detail and want to present your company in the best light.  Although trends change, most companies today favor a "business casual" dress policy. 

For men, this often means khakis, collared shirt, and possibly a sweater.  For women, the lines blur a bit more simply because they have more choices.  If in doubt, ask professionals you trust and remember that dressing conservatively is always best.

General Recommendations

• Regardless of the company, it is never appropriate to wear sexy, tight, sloppy, or flashy clothing to work. 
• Purchase quality clothing rather than a large selection of outfits.  Not only will they last longer, but they will also typically fit and look better.  Using accessories wisely can easily change a person's look.
• Less conspicuous colors will allow you more versatility in your wardrobe.
• Dry clean suits, woolens, and silks as needed.
• Ensure a perfect fit by having your clothing tailored.
• Purchase overcoats for both winter and spring.  Don't ruin your professional look with a casual jacket thrown over your work clothing.
• Typically, do not dress better than the top leaders in your organization.
• Many companies permit dress-down Fridays where jeans may be acceptable.
• Avoid athletic shoes and sandals.

Remember, expressing your personality isn't nearly as important as gaining respect at work.