Always backup your important data that you might need after you install a new custom ROM, an official software update or anything else. Make a backup for just in case, you never know when anything might go wrong. See below for some tips on how to backup data:
§ Backup your SMS messages. How? –> How to Backup/Restore SMS Messages.
§ Backup Contacts, Gmail and Google Data. How? –> Sync with Google Sync.
§ Backup Call History. How? –> How to Backup Call History.
§ Backup WhatsApp Messages. How? –> How to Backup/Restore WhatsApp Messages.
§ Backup APN Settings: GPRS, 3G, MMS Settings. How? Note down everything from: Settings > Wireless & Networks (More…) > Mobile networks > Access Point Names.
Samsung users can also back up data using Samsung KIES. If you backup data manually, you get more options what to choose from and it is very easy to move data across Android devices from different manufacturers, i.e moving Samsung Galaxy Note backup data to HTC One X.
If you already have a custom recovery (ClockworkMod, TWRP etc.) installed on your phone, we strongly recommend a backup using that as it creates a complete image of your existing phone set up.