The problem with pneumonics is well, you have to remember the pneumonic. If your student can memorize what all those letters mean, then they are sure as hell capable of learning a flow and what the systems do.
Mnemonic devices are great if they're small enough to be effective. Any mnemonic I come up with is no longer than 9, and frankly, I'd prefer as low as possible. There's some science behind this too:
http://en.wikipedia.org/wiki/The_Magical_Number_Seven,_Plus_or_Minus_Two
Consider this, the super easy mnemonics or flows are usually pretty short.
Mixtures, Props, Throttles - Full Forward
Gear - Up
Flaps - Up
Identify
Verify
Feather
Secure
(7 Items, or 9 depending on how you're counting)
CIGARTAB (I use this in the Navajo daily prior to takeoff)
Controls - Checked
Instruments - Checked
Gas - Inboard Tanks
Avionics - Programmed / Set Up
Radios - Set For Departure
Trim - Set
Annunciators - Extinguished or Considered
Briefing - Complete
F-GUMPPs (Another Thing I use to back up my Flow and Checklist on the Jo)
Flaps - Set
Gas - Inboards
Undercarriage - Down and Locked
Mixture - Full Rich
Props - Set
Pumps - On
That covers everything that is liable to kill me when I'm landing
I still remember mnemonics from early training including "Turn, Time, Twist, Throttle, Talk," PTAEN (Position, Time, Altitude, ETA to Next Fix), 3-152/5-111, and a whole host of other useful ones that still pop up occasionally flying SPIFR. As long as they're short and sweet, you shouldn't have any problem keeping them in your head. The most important one?
Now that I'm flying an airplane with a decent autopilot, one I use
all the time (every time I make an Autopilot change, or a nav change) is "PFNF" - "Use when the
Pilot
Flying is
Not
Flying." That is:
Programming - Check your avionics, make sure it's set to the desired fix or navaid
Final Approach Course - This is critical, and has come close to screwing me up when I've set a course to something near it and not caught it until the last minute when I wonder why the A/P is hunting so hard.
Nav Source - this is an easy preventable "gotcha," if you're wondering why the autopilot isn't capturing the GS or following the course you want, this maybe why - you're still probably in GPS, or didn't cancel suspend to fly the missed, or whatever.
Flight Director / Autopilot - did you set this up right? A quick glance at the A/P panel has kept me from flying off course because I left the system in heading mode, or didn't enable "GPS Steering" or something equally stupid.
That covers the easiest automation mistakes that I've made, and according to my boss is what he's seen the most flying with other guys in the Lears and King Airs and Hercs over the years.