The first impression is important as this sets the tone for your future workplace relationships. First impressions are based upon your actions, comments, dress, and non-verbal behaviour.
Because you observed how others were dressed at your interview, you already know how to dress on your first day. If you have received a written policy concerning dress, then the first day will be even less confusing. If you are to wear a uniform, make sure it fits, is clean and wrinkle free.
In addition to what you say, your body language conveys a powerful message about what you are thinking and feeling. Try to relax and avoid having your body language contradict your verbal message. A few ideas that may help to convey the appropriate message include:
Be an active listener
Speak confidently, avoid mumbling
Shake your fellow employees hands with confidence
Look people in the eye when you are introduced
Offer a warm smile
Try and remember the names of the people you meet. Of course it would be unrealistic, not to mention nearly impossible, to remember everyone's name, but...
Strategies for Remembering Names
Work on remembering a few each day, pay particular attention to those people you will be working with directly.
Write names down and go over them in the evening, or use word association techniques.
Don't be afraid to ask. Asking someone whose name you remember for someone's name you've forgotten is the least awkward.
What to Expect on the First Day
People may ignore you. They may go on with their business without noticing you are there, or may embarrass you just for fun as an initiation to the workplace. Remember, you will not be the "new" person forever.
People may also go out of their way to welcome you to the company.
High emotions, excitement, anticipation, nervousness, anxiety, fear.
Surviving the First Day
Be humble, being nervous is natural.
Be nice to others first; don't wait for them to be nice to you.
Have a sincere desire to join the group, let them know either verbally or non-verbally you want to be a contributing team member.
Try to do everything in your power to have a positive start.
Observe what is going on around you in the workplace, this will give you a clearer definition of the way things work.