I'm upgrading from the S3 to the S6 and I'm wondering what I need to do in advance to prepare for the transition? From pics to contacts, to apps, to cloud storage. Please share your pre-purchase steps...thanks!
Assuming you have your contacts and calendar set to sync through Google you shouldn't have to do anything there. Text messages and pictures will not be backed up though. You can back them up locally or sign up for a cloud service like One Drive or Google Drive and just back up all your stuff there.
I personally don't care about saving my texts so I can't tell you how to back those up, but I do have my pictures automatically syncing to the cloud. I will not re-download them onto my phone but you will still be able to access them on your new phone through the cloud.
Other things I do is just take screenshots of how I have my screens set up since it can be hard to remember which apps to download again.