how do i start talking to him?

So if あなた saw my 前 entry, "does he like me... または not?", あなた probably 発言しました he does indeed like me. If あなた haven't read it yet, then あなた should probably go and check it out so everything makes もっと見る sense.

Two people コメントしました saying that they assumed he liked me and I should try talking to him. Thing is... I don't necessarily know where to start. It's not like I'm a complete stranger to him - I've talked to him before, it's just that conversations don't go the way that I plan them too. Either we're too shy to say something else, または someone barges in and takes the limelight, so he ends up talking to them and not me.
As I 発言しました before, this guy is one of the most 人気 boys in school and he's extremely musically talented. He loves playing ピアノ and preforming magic tricks. He's quite weird, actually, and he's pretty poetic. He likes 芝居 and is probably one of the best singers I've ever heard for our age.
Again, I don't know what kind of topics to start talking about... I've always had this extremely high social anxiety level since I was bullied mercilessly in the past. I don't have any フレンズ (literally, I'm not exaggerating) and I find it hard to make friends. Let alone talk to the guy I like! So what can I do to start a conversation with him?