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