you can say that "onamae wo oshiete itadakemasuka?(お名前を教えていただけますか？）or "onamae wa nanto oyomishimasuka?(お名前は、なんとおよみしますか？）－could you tell me your name of pronunciation? sometimes, it is difficult to read and prununce person's name. when you can not prununce well and forgot person's name, you can ask like this.

Are you talking about how to ask in real life, or online

O-namae wa nan desu ka? Is the basic way to ask. You can change desu to deshou for more formality. Just never use o- with your name.