How to behave at the client location?

Attitude makes a lot of difference. If you have a good attitude with required skills, you are the winner. The following tips may help you.

Be humble and polite to your co-workers and others.

Do not criticize anyone. That is not your job.
Always be professional and do not take any thing personal.
Be friendly with your opposite sex collegues and do not get involved in any sexual litigations
Do not break the client dress code. It is not a good idea to go to the office in jeans and sneakers even if they have a casual dress code.
Light cologne is fine but do not use strong perfume.
Do not talk loudly when you talk over the phone or to your collegues. Talk in a soft and clear voice.
If you have any dental problems, make a dental appointment with your dentist. If dental problems go unchecked, they lead to embarassing situations involving bad breath. Have breath mints, chewing gum or peanuts in your desk. Check your breath before talking to your collegues personally.
Wear fresh and neat clothes.
Always be punctual.
Complete your assigned task within the time frame. Do not postpone it.
Do not talk about politics and religion in the office premisis.
If you are invited for a happy hour party or any party try to attend it atleast for some time. That is the best place to know more about your collegues.
Do not play music loudly.
Be as easy going. Do not get the "tough guy" label.
Attend meetings regularly.
Be enthusiastic.
Try to be helpful to your co-workers.
Be a good listener. Do not interrupt when someone else is talking.
Discuss but do not argue.
Do not lose your credibility