Children are precious, sweet and temporary. Temporary because childhood ends typically at age 18. The love for your child obviously goes a lifetime as they enter various phases of life.
Catholic and other Christian parents have parenting difficult. Media and society are constantly pushing sex before marriage, divorce, provocative dressing, cursing and other anti Christian themes on a daily basis. How do you handle the constant pressure?
Honesty is the best policy. Teaching your kids firm morals and the reasoning behind them is important. If you just tell them not to do something, they are more likely to want to do it or try something.
The good old, "But, Billy is allowed so why can't I?" I think every parent has heard this line. Stay calm and explain why. Pouting and moping might come afterwards, but remember you are their parent. You aren't here to be their best friend even if that is the easy solution.
Prayer is beyond words essential. Pray for their health, safety, education and choices. Let them know that you are praying for them.