It depends for me. Some people, if there's a common passion or experience we have, then I take initiative and speak with them. Others, if I really admire a person, sometimes I may find it difficult to approach them and wait for them to come over to me, or at least show amicable signs. I don't always follow the leader though. It all depends on context. If it's friendly, it's easier. But when it's in a more formal setting, I tend to be less initiating.