The main thing to remember is that as a parent, you are their authority, not their friend. The minute you become their friend, you lose your authority and credibility as an authority figure. It is our job as parents, to teach our children about morals, compassion, selflessness, hard work, self-discipline, honesty, etc. Our role is to train them up in the way they should go so that when they are old, they do not depart from it.
Being the fun one and allowing the kids to do whatever they want is not being a good parent. Kids needs structure and discipline. Whether they realize it or not, the want and need boundaries.