Here's what I use (my Operative uses the exact same setup):
Out of cover.
In cover.
DPS skills are on the left, the bottom bar is all the healing abilities and some random things that are consistently bound across all characters (interrupt, warzone consumables and throw huttball), the top right is things on a long(ish) cooldown. Underneath that is stealth things and scamper. To the right of that is travel stuff (quick travel, priority transports etc) and to the right of that is things I don't really need to keybind (buff, recuperate, mount etc).
(Sabotage charge and XS Freighter Flyby are on the bottom so that I can see the cooldowns, but I only use them from cover.)
I don't use ctrl to keybind because I find it's awkward to reach, instead I use a Razer Anansi keyboard and can easily reach the shift, alt and ctrl+shift key.