Don't gossip. Keep a journal if you need an outlet. Or if you must gossip make it positive.
Be neutral and friendly to everyone until you know who the backstabbers/helpful ones are. Learn who you can trust and who can't keep their gobs shut.
Beware of the early on overly friendly brigade. There'll almost always be at least one.
Check everything.
Take notes
Take every opportunity you can for training and make sure any mandatory training is up to date.
Be clear about objectives, company values, appraisals etc.
Your coworkers are (mostly) not your friends.
Ask a manager and mindtools are great websites.
Beware HR. They're usually not your friends either. Make sure they confirm everything in an email. Keep scans, downloads and paper copies of payslips, contracts and other important documents.
Nod and smile. Pretend you're enthusiastic even if you're not.
Be very, very careful about what you share about yourself, especially in the early days. You never know who might use it against you/get offended.
Under-promise and over-deliver but do what you say you will.
Be prepared for constantly moving goalposts and don't call anyone out in public.
Keep good records. You never know when you'll need them.
Dress appropriately for the setting.
Have an exit strategy just in case - a one year, two year, three year and five year plan.
Join a union.
Too many people focus on pleasing higher ups all the time. While that is important, don't assume any of those people are there for the long haul. Be prepared for your boss/mentor/work bestie to move jobs/organizations in the future.
Be nice to receptionists, cleaners, support staff, people higher up often have no clue just how important and knowledgeable they are. They see EVERYTHING.
If all else fails, think about each day like a work sitcom.
Remember we work to live, not live to work.
Eat sensibly, take breaks and invest in a good flask or insulated cup. Carry an umbrella and/or an appropriate waterproof and always have a snack bar on you in case those very important meetings over run. Be prepared to eat lunch in your car qor other safe place if surrounded by gossips.
Best of luck!