Hye Assalamualaikum,
Today I want to talk about the etiquette when you are a newcomer.
Firstly don't 'SHOW-OFFS'. It is rude and useless to try to impress old timers by telling them how much better your old company handled matters or to point out mistake you see them making.Once you have established a working relationship with the other workers and with the manager,this is because your suggestions stand a much better chance of being accepted instead of resented.
Secondly is 'TOO FREINDLY TOO SOON'.Use some restrain in yourfirst few days on a new job.Give those already on the job a chance to make the freindly advances.
Thirdly is 'WHEN YOU ARE INVITED TO LUNCH'.Here are some tips, on our first day, a few persons may ask you to have lunch with them. Generally, you are expected to pay for your own lunch, even if your immediate superior is in the group.If you immediate superior invites you to have lunch with him or her alone,generally the superior pays for your lunch.
Lastly is 'USE OF FIRST NAMES IN THE OFFICE'. Basically, most modern offices are informal, and the use of first names among fellow employees is the usual practice. Nowadays, even in such office, there are situations where it is improper not to use a title (Mr.,Miss., Ms.,)and the last name.
Remember; the basic and most importnt rule is simple: you may follow the practice that has been established in your particular office.