best way to change my Apple id on iPhone

Years ago my wife and I shared my apple id.  She now has her own account and id, but we still see linking in our calendar and other places - unwanted linking, but cannot seperate it.

I'm getting a new device in a couple of days and want to be able to link with my self only.  I'm guessing creating an all new id is going to be my solution.

Any advice on the best way to set up a new id, and keep all of my paid for apps?