If you want use a Jellybean/Kitkat ROM firstly you should upgrade your device to stock 4.1.2 otherwise get ready for brick.
2. Flashing CoCore kernel when you're using AOSP ROMs
Also you can't use this perfect kernel on AOSP ROMs (Cyano-AOKP-PA...) For some reason cocafe didn't add support for these ROMs. But AOSP kernels are based on CoCore. Shortly don't try to flash CoCore kernel on AOSP ROMs.
3. Writing false code in terminal
As you remember; early of our development there wasn't simple tools like UKF (and Triangle Away didn't support us.) You had to write DD codes in Terminal Emulator for flashing kernel and resetting warranty. Stretch out your fingers because even if you write false a single letter GUESS WHAT hardbrick.
4. Disconnecting your Odin process
Don't f*ck with Odin when he works with your device. (AKA rooting, recovery or firmware flash) If you disconnect your device at the false time, maybe you won't see Android anymore.
5. Flashing a China ROM when you're using Un-China device
Yes they have different things in their firmwares. If you didn't buy your Janice from China don't flash China firmwares.
6. Flashing a Gingerbread ROM when you're using Jellybean
You can't simply downgrade your device. You should have proper files for downgrading after you can flash any Gingerbread ROM/Firmware. MORE INFO
7. Ticking Re-Partition
If you're using Janice, re-partition is here for only downgrading. Don't use if you're rooting/flashing a regular firmware.
8. Dirty Installs
Clean install comes with stability. Dirty install might causes bootloops, softbricks or errors. It's your choice.
A hammer can cause too much thing.