I never go in any particular order....obviously ROM has to be first. Then I will almost always go Gapps then kernel, then any extras. I'm different from OCN in that I flash everything in the same recovery session. Using Amon RA 2.3 I've never had any issues. I always flash dt a2sd prior to restoring apps. After my phone boots for the first time (so prior to restoring anything via titanium) I will normally run the a2sd reinstall command in terminal emulator to ensure that the script will put everything in my partition, then after the phone reboots, restore everything from Titanium
Then for good measure, fix permissions after everything is done.