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.