pynna
Secondary duties enable NCOs and Officers (and some junior ranks too) to demonstrate breadth by expanding knowledge and interests outside the primary role. They also show that you have extra capacity for responsibility at a particular stage of your career.
What you should take from this is that you need to get your primary duty squared away before you take on extra duties. In reality, as Fritz says, you should be shielded from these extra duties by your chain of command until they believe you are at that stage of your career. During phase 1 training (for both Officers and Non-Commissioned Aircrew) you will be given opportunities to learn about and practice secondary duties during the course (or at least you were when I went through, but that was the same course as Pontious).
Points to note for secondary duties:
a. Do not collect them like Scout badges
b. Carry out one higher profile Station duty well, rather than several Sqn ones less effectively
c. Remember it is a 'SECONDARY DUTY', do not allow it to take precedence over your primary day job.
d. Work your way up the secondary duty ladder, eg if on the mess committee start off on the Ents sub-committee, then treasurer, before the Stn Cdr realises your potential and appoints you to PMC /CMC
e. In a similar vein to c. ensure you strike the right work/life balance. Saddest things I saw was a Sqn Ldr who had to move into the mess during his final tour before retirement as his marriage had broken down. He'd spent his whole career being focussed on the RAF and forgot what should have been the most important thing in his life. His family.
In trying to make yourself competitive on promotion / re-engagement boards, don't forget the big world beyond the wire. There are plenty of opportunities to volunteer in the local community, carry out charity work and generally make yourself useful outside the RAF. I've known lots of folk who help to run the local cadets / guides and scouts / village committees etc etc.
Finally, after embedding yourself in your secondary duty / community work, ensure that when it comes to appraisal time, you let your 1st reporting officer (1RO) ie line manager know what you've done over the year and, more importantly, how you've done it. If you can get a genuine endorsement from the OIC of your particular secondary function, that would be good. Anything you can do to make your appraisal writer's life easy, will be good for you.
But take things one step at a time, sort out your basic and professional training first. There'll be plenty of time for secondary duties in the years to come.
Ikky