Apple music service is live now. Here is the way to start using this service and prevent paying even after free trial expires.
iPhone and iPad
First thing you need to do is to update your OS to iOS 8.4 for that goto “Software Update” in “Settings” on your iPhone or iPad.
After you update your OS to iOS 8.4 your Music icon will turn Shiny rather Orange of earlier versions.
Open it and click on “Start 3 month free trial”. Next you will be asked about Genre you like and after that you will be asked to “ Choose three or more of your favorite artists ”. When you press “Done“ Apple will suggest you songs based on your taste.
Now, to prevent paying even after the trial expires follow these steps or else after three months you would have to choose a membership plan ( individual £9.99 / month after trial ends ) or ( Family up to six members £14.99 / month after trial expires )