K.U.
It depends on how much you want to live on once you retire. Then, generally, if you can withdraw and live on 4% a year of that total amount, theoretically, you will never run out because your money will still be gaining more (5% for conservative investments) than you are taking out (so $40,000 per year would be 4% of $1,000,000). Can you talk to your parents to find out what they have done to fund their retirement?
Whenever I've worked anywhere that offered a 401K, I put in 10% of my paycheck. I just started a new job in June and will be eligible for their 401K after a year, so I am thinking of increasing it to 20%. Meeting with a financial adviser might be helpful, in knowing what your goals are and how to best get there. The Motley Fool website, at http://www.fool.com/, is a good resource too (example: http://www.fool.com/how-to-invest/thirteen-steps/step-11-....
I also like watching Suze Orman and seeing what advice she gives for people in different situations.