My first instinct was to say "Hey!! That's not fair!" But after thinking about it, Violet & Bott are right. Having someone just walk up to me and say "Hey I noticed you are hearing, my name is ..." would make me feel pretty awkward.
I think however if you found something in common that you really did want to start a conversation about:
"I like your sweater"
"That looks really tasty, may I ask what it is?"
"Is that the new phone/ereader/electronic toy? Do you like it? I love mine"
The interest in talking to someone should be the interest in the person themselves, not just because they are Deaf. Let the other person lead in actually continuing the conversation.
If you want more practice in just signing, then the best bet is probably the skype/chat hookup board here.
