What to do when you feel uneasy about a stranger?

I took the bus to Long Beach county because I had a study abroad meeting there. Well, I got lost. I knew I was close to my destination but I couldn't tell if I was going the right way. I asked a young man for directions, he was heading the same way I was going. He seemed nice and introduced himself but I think he may have had some alcohol in his system. Anyway, I am trying my best to follow Google maps when he says that he will take me there and that he knows a shortcut. He said to follow him through this parking lot.(I can be a little trusting and naive but I knew enough to know that a dark parking lot with a strange man is DANGEROUS). I seen lights and a sign up ahead that looked like the place I was supposed to be. Yes, I was totally and completely freaked out. Thankfully, while he was heading toward the lot there was a barrier which I got on the other side of. I was being super polite (I have no idea why because he was trying to lead me the opposite direction)

Basically how do you handle a situation like that? I don't think being polite was the best move lol