Think about a place near you that is full of people from teens to older people where they are just walking around, hanging out.
After that first sentence I feel like I'm going into a mentalist effect haha! What if I named this place you were thinking of? lol!
Anyhow, malls are always good, book stores, coffee shops, etc. We go perform at a place called the Woodlands. It is an outdoor shopping center (with a mall right next to it) and we just walk around, go into the book store, starbucks, and perform for people outside.
Where ever you go, you want to try to catch people that are just hanging out. Read the people before you go up to them (hell even evesdrop if you have to...I'll go into that in a sec. lol) If the person(s) look in a rush or remotely busy, or like they are trying to get somewhere, don't approach them.
The reason I said evesdrop is because there was this group of guys who looked like they were just chillin hanging out. My friend Cody walks up to them and asks if they'd like to see some magic. They looked at him and said "Dude, we are having a discussion about God." Luckily, one guy stepped out to talk to us about God and also let us show him some magic.
Ultimately, we were there for roughly 8-10 hours just hanging out and performing...if you count the above story, we got turned down twice the entire time.