Probably the most important benefit is the medical plan. You will have to decide for yourself how well a company's plan fits your needs. For instance, do you have a family that needs a comprehensive medical plan, or are you single and healthy, considering some other benefit to be more important. Your medical insurance may be free or a copayment may be required. Also, your family may or may not be covered, and if they are covered, another copayment may be required.
Another important benefit is a 40IK retirement plan. It is well worth enrolling in a 401K since the money is withdrawn from your check before taxes are taken out. Therefore, the tax that you owe on that money will be deferred until you retire. Find out how much, if any, the company matches your contribution. Some companies only match a little, while others match a lot, essentially using the 40IK as a joint company/ employee-funded retirement plan.
In some instances, there will also be a company-funded retirement plan. This may be in the form of profit sharing or a set amount of money that is invested for you, or it may be in the form of company stock issued to you. Try to find out when you will become vested (how long you must be employed before you have an ownership right to the funds), approximately how much you will receive each year, as well as when and how you can get your money out of the plan.
There may also be term life insurance provided by the company as a free benefit. They may also offer additional insurance that you can purchase for a reasonable cost to cover such things as short-term disability, long-term disability, and dependent coverage.
Find out what you will be paid for holidays, vacation, sick or personal days, and what it takes to qualify. Be sure to ask when you will be eligible for these benefits. Often, there is a waiting period of 30-90 days, or even a year before you can participate in these plans.