Don't be afraid to experiment, but "partying" should be kept to a minimum and only for socializing. Also, avoid debt as much as you realistically can. If you're taking out loans for school, don't be afraid to pick up a flexible part time job doing retail or waiting tables (this helped me keep my student loans much lower than they could have been). Source: personal experience
I was a hardcore party type in my 20'. Some say that I overdid it but I have no regrets. I am now in my 40' and still party.