This can be further expanded.
Originally Posted by orcstar
You should have (albeit obscure) keybindings for any and all abilities you could ever need midfight - i.e.: while you're busy using the mouse for movement.
On the flipside, you should have clickable buttons, even if on a minimized auto-hiding bar somewhere in the corner, even for the super-spam-keybound abilities. Just in case you can't hit it right now because you're busy doing some obscure strafe-movement.
This allows you to freely use clicking OR keys for each and every ability.
The big upside of this is that independant of which specific fight mechanic ties up which hand right now, you can always trigger an ability.
I usually click my totems from Totemtimers. However, Tremor Totem, Cleansing Totem and Mana Tide Totem I got on keybinds since depending on the fight I may have to drop one right that very moment.
I do generally key-trigger ~15 of my char's abilities, while clicking the rest. However I frequently find myself click keybound abilities or keypressing clicked abilities. It's just one annoyance I wanted to get rid of and once I did it worked out pretty well.
-- (The Death of Rats, Terry Pratchett, Soul Music)