What are some best practices for a family sharing a single Apple ID?

Here is what I do, where I share one appleid for purchases among 3 family members. Number one, only use the appleid for purchases just for purchases. then, each member should have a separate iCloud account with a unique appleid for mail, contacts, iCal, etc syncing. Then, on all devices set the appleid for the store to the purchase id and on the individual devices set the iCloud id to the appleid for each individual separately. Works great for me.

My family's system consists of using a shared Apple ID to buy from iTunes and the Mac App Store. Each member then has their own iCloud account based on a unique email address for Mail & Notes, Contacts, and Calendars.

On the iPhone: everyone should enter the shared Apple ID under the Settings/Store/Apple ID section for purchases. Each user can then enter their own iCloud for all other data in Settings/iCloud.

On the Mac: everyone should authorize their iTunes and Mac App Store accounts under the shared Apple ID by signing in under the Store menu in iTunes and Mac App Store. Each user can enter their own iCloud account for all other data under System Preferences/iCloud.

For both iPhone and Mac: My family shares calendars. If you want to share Mail & Notes, Contacts, or Calendars, add the person's iCloud account to Settings or System Preferences/Mail, Contacts & Calendars. Then choose what you want to share.