Getting your first job in the U.S.  is obviously going ot be a big deal. Some cultural difference about the work ethic might confuse you or shock you, some of the administrative paperwork probably will loose you..

What to expect:

Everything is going to depend on which type of company you will work for. I cannot stress that enough. However, during my personnal experience, I have encountered som simiralities.

First do not expect much more than 2 weeks vacation a year and a few holidays such as labor day. There is going to be no comparison to your life in Europe or other place of the world... and you will feel that in many different ways.

Work seems more important since it is the main occupation, vacation ARE a luxury, most people I worked with took long weekend but not vacation.

Pay should usually be higher than what you got back in Europe, if you were in europe, but remember that you will more everyday expense too.

Overtime shall be paid 1.5 times your usual rate (except if you are salaried in which case you just get a fixed wage),there should be  a policy in you company as to how many sick days you can take.

A good job should offer you decent wage, but also health insurance and eventually dental and life. This is important because a good insurance provided by your employer could save you a few hundreds dollars a month.

Your usual notice should be 2 weeks. The employment laws are much looser than in most european countries.

One piece of advice: your european mentality might not always be welcome so be careful to seize the spirit of the company and your co-workers before critizing or commenting on any of the company's policies.

It is also common to be shown a bunch of videos about sex harrassment at work or other safety policies.. Don't panic, this is pretty usual..that and drug tests.(especially in staffing agencies, not really on your average job)