akula: there was a "report" from the NCA promotion board going around the Green and Gold Sqn a few weeks ago. It contained a couple of A4 pages' worth of the Board's thoughts on both the reports and the candidates they've looked at in the last year, and the closest you'll get to "tips" from them (eg, one big secondary duty is better than lots of little ones, ROs with a grasp of the English Language help, etc).
I reckon it's worth trying to chase up. Grab me in work or PM me if you need help finding it.
d