Should I contact brokers from banners put up on buildings and lamp posts?

So I have to shift to HSR layout in about a month's time. I'm already based in JP Nagar, so I'll explore the area and try to look for accommodation. But what options should I pursue? Should I find listings online and go check them out, or should I call the numbers on banners which are everywhere, or should I ask random strangers living in the area I want?