To me, it's all about shared experiences and shared interests. It doesn't have to be shared passions, but you've got to be able to at least appreciate mine and I have to appreciate yours. For example, my wife will sit and watch EPL soccer with me, she knows what's going on and enjoys the games. She wouldn't be watching it if it weren't for me, but she does it with me. I watch Project Runway with her and have learned a lot about the fashion industry from it. We sit and discuss the designs and challenges as we watch even though I would never watch it without her.
I love it when people can share this with me.
The problem is that if people have different definitions of "friendly," you can end up thinking you're being friendly, but missing the mark by a wide margin. Someone who is cheerful, but can't appreciate my passions is at best indifferent to me. By the same token, if my daughter and I both enjoy watching Jeopardy, but I talk about people behind their backs, I'm not very "friendly" to her.
What's your definition?*
* - Posts that end with questions almost never seem to generate a response on this blog. It's an act of pure optimism to try it yet again. :-)