[Xperia Z1 Compact General] packetfire:
As an aside to others, followed this approach on a refurb Xperia Z1 Compact at .386 due to OTA updates from Sony.

1) First problem was rooting, as backing up TA partition, bootloader unlocking, installing recovery and everything else first depends on having root.

A roadmap of tools would be a BIG help for newbies. I am not qualified to draw up such a map, but too many tool "tutorials" offer instructions without context to the larger picture of the many prerequisites to using that tool. Starting at "I just bought a phone", there seems to only be a few viable paths to "I have Xposed installed". Not my place to criticize, but this is NOT a process I would allow my 93-year-old mother-in-law to attempt, and if she cannot follow the instructions, then there is a need for a roadmap.

1a) Most of the tools with which one obtains root require one to have an unlocked bootloader, and/or suggest the TA partition be backed up, so again, root had to come first.

1b) The sole exception to this was "TA-Backup", which works without needing the phone modded in anyway, and is documented clearly (big up to de developers and documenters, mon!)

2) The choice on rooting seemed somewhat sketchy - KingRoot. Lots of paranoia over a server-based approach to providing the right exploit for the phone at hand, but the inability to remove it with SuperSu seems to vindicate those who claim that KingRoot is unethical in basic intent, rather than working for the user. It worked great, but my wager is that this will turn out to be another subsidiary of the Chinese military, with aims to install something... special on certain phones to assist them in their efforts to commit industrial espionage. I have no data of value, so I used it to get root, knowing that this package would replace it.

2a) After root was obtained, Titanium Backup was installed and used to create backups of the apps and their data, including the user set-up. In retrospect, this may have been a mistake, given that there was little that was installed or used that was not installed via the USB cable.

3) Bootloader unlock was done "per Sony instructions" on their webpage, which required the download and updating of both java development kit and the android development kit. (There has to be a small subset of all that that can be packaged for those who merely want to unlock a bootloader, rather that start a career as a coder of apps, but I digress.)

3) Installation of a recovery was done, and a second backup of the TA partition was done, even though the excellent "TA-Backup" had already been used.

4) An SD card was loaded up, and recovery was booted into, and it promptly seemed that the phone had been bricked. After several forced power-downs and power-ups with the power and volume keys, the phone booted into normalcy.

5) Restoring the Titanium backup of the apps and user accounts may have been an error in judgement, as the result was an inability to use the Google Play Store - first error was RH-09, then, after clearing app data and cache for all of Google Play Services, Downloader, and Google Play Store, the error changed to RH-01. Subsequent steps included changing time to a past time (to mess up the sync), and clearing app data for the same Play Store-related apps resolved the issue, and the clue was a notification that "apps needed updating".

Dare I attempt to install Xposed? I dunno, I think I will wait a bit, and read some more, as going 5 years on the same Android 2.x phone put me out of touch with the current state of phone modding.

With luck, someone else will find this of some use. Two "scary" events, both likely explained by the lack of a road map to explain the order in which the various tutorials should be followed.

Thanks to everyone who wrote code to make it easy for me to be both stupid and critical of their hard work! ;)