Below mentioned essentials are only for people who plan to stay in the US for long term.
SSN : Social security number is a must for anything in the US.To rent a house, to own a credit car, Driving license, to buy a car and many such basic needs. You cannot apply for a SSN until the information about the non immigrant with valid work permit reaches US govt through DHS.DHS is Department of Homeland security.US Govt suggests you wait for 10days before applying for SSN.Once the information is in the database you are good to apply for one.After making an application it takes 4-6 weeks for the SSN card to be delivered.
For more information visit http://www.ssa.gov/pubs/10096.html
Credit Card: Second most essential to have here in US is the credit card. All financial trasactions that happens on a day to day basis has to be done either through Credit card or Cash. It is good if done through credit card. Reason,it is necessary that you build a credit history for any future investments like buying a Car or loan .
Only after you own SSN,Credit card and start building your credit history, living becomes a bit easy.
Next important necessity is Driving. In places where public transport is nill it is important that you know driving.
Driving in the US is easy for 2 reasons
1. Auto transmission cars
2.People follow strict traffic rules.
You could see only 4 wheehlers here on roads.Rarely you see a 2 wheeler.
Unless you have SSN and a permanent address to stay you cannot get a driving license.
So take care of the three things and get start your living.
Any information or suggestions are welcome to comment. It will help you,me and others in need.