I gotta say... I'm quite shallow. Most of the time it's based on looks. Whether it's a pretty or unique/uncommon character model, or a neat looking outfit, you got my attention. Then I might have a quick look at their search info and FC. I only really look at wikis if it's someone I've heard of before and particularly interested in or if I'm unsure how to approach. Sending a tell is usually how I go forward.
Also, I'll walk up if someone's already roleplaying and it's actually interesting. It's sometimes rare since I get a little bored by generic "I'm an adventurer from Ul'dah! What's your name?" tavern chatter. If someone's roleplay is entertaining to read and there's a definite hook for my character to get involved, you bet your arse I'll walk up, or at least send a friend request and ask for roleplay sometime later.
Also, I'll walk up if someone's already roleplaying and it's actually interesting. It's sometimes rare since I get a little bored by generic "I'm an adventurer from Ul'dah! What's your name?" tavern chatter. If someone's roleplay is entertaining to read and there's a definite hook for my character to get involved, you bet your arse I'll walk up, or at least send a friend request and ask for roleplay sometime later.