How to Change My Apple ID?

My mom, two sisters and I all share the same Apple ID. It's been working fine for us until recently. I'm starting to get irritated that we can all read each others' texts, see each others' pictures, share each others' money and download each others' songs. In addition to that, I have all of my mom's contacts in my phone. It also doesn't work when I tried to use 12 Gifts, that new app from Apple. It bases everything off of all of our purchases, not just mine, and gives me things I don't want. I'm really starting to get fed up with all of this.

I have my own Apple ID, I just don't know how to set it as my ID rather than changing the ID for all of us. How can I do this without affecting my mom/sisters? And how should I transfer my information to my new Apple ID once it's set up?

(PS: If it helps, I have an iPhone 4 and a MacBook Pro, my mom has an iPad Mini and an iPhone 5, and my sisters both have the iPod Touch 4G)