For the first few days on the job err on the side of conservative. Watch how your peers and your boss dress. You will then have a sense of the right type of clothing to wear. Dressing like the boss is usually the best idea. It shows your desire to be a part of the organization. Remember these points:
If you are still in doubt ask for an employee manual. Most companies have written guidelines that include dress codes. Reading the manual will not only give you a sense of what to wear, but will also give you clues on what is expected of you as an employee.
On occasion, check yourself out. Ask yourself: "Would I be comfortable with my appearance if I had to have a meeting with my boss or another manager?" Think as a professional and reflect that in your daily appearance.
Find a buddy to help you adjust to the new job. Often times you are assigned a mentor. If not, after you are there a few days, look for someone you think you will get along with and ask them to help you out.
How you look represents the company. To customers, you are the company. Also, your appearance can directly affect your relationship with others on the job and the work environment. Therefore you should consider your appearance for work, not for yourself.