Every official has a pre-play system to run through to prepare for the play. Here is a good one for wings:

A-Assignments
B-ball (watch for quick snap)
C-clock (close to period end?)
D-down/distance (know where first down is for clock kill)
E-encroachment
F-false starts (shut it down)

Does anyone have one for another position?

G-game sense (use when all else fails)

;)

Here's one for downfield officials
 

For down field officials (FJ, BJ, SJ), this is more of a concentration routine:
· Clock
· Down and Distance
· Count players
· Who’s eligible?
· # of key and # of defender
· PLAY
· DB Officiating
. Substitutions and ball duties
Repeat sequence
· Clock...

Wish it had a nice mneumonic like your A,B,C,D,...
One thing I learned, don't be afraid to say these things out loud to yourself. Even though it sounds like you're talking to yourself, it helps you remember by hearing it. Putting one more sense to work can make the difference between remembering something and forgetting it.