How do I talk to a friend without making her mad?

Ok so to make a long story short I have this friend who got dumped by a guy last week. This guy who dumped her wasn't a very good guy anyway. But I'm worried about her current choices. She's been driving 20 miles to see a new guy who I believe is a drinker and a pot smoker. I don't know who else she would be holding pot for in her car. Well yesterday she was caught speeding and got a 40 dollar ticket. She's lucky the highway patrol officer didn't get her for the pot. She admitted that Saturday night she drank with this guy, stayed out till 1 AM and then drove home. I really want to tell her how I feel about what she's doing. But I don't want her to get pissed off and do something even more stupid. I just don't want her to get hit with a DUI or worse killed in a car accident.