I got to make a comment here, so that members of the public that inadvertently click in on this site don't get the impression that this is the prevailant skill level of the crew that fly them today.
First of all, In my opinion, the captain is not "made" at an upgrade course.
The captain candidate begins his or her preparation from the beginning of their flight training (commanding Cessnas and Pipers). And of course continue that preparation during the time being a F/O.
If the F/O didn't think of "what if" scenarios, or paid attention to how the captain handled various situations (fuel calculations, pax, MEL, weather etc.) during their
whole career as a F/O, then it's because the airline that hired said F/O has insufficient screening methods (again for the inadvertant public - avoid these airlines like the plauge).
Likewise should the F/O
of course know the limitations, systems and procedures as well, or preferably
better than the average captain - since he perhaps forgot some / replaced other of it with experience/feel (that the young F/O doesn't have yet). If the F/O thinks that this is not important until he is in an upgrade course, something somewhere along the way (beginning?) went terribly wrong with that F/Os attitude.
A F/O, should feel equally responsible for every flight as the captains. E.g. never leave ground with out cross checking fuel calculations and check and approve the actions incase of something being MEL'ed (question/learning if disagreement), just to name a few examples. The F/O should challenge the captain in any situation where something is not done to their liking and demand to be educated (or a new course of action to be taken if no arguments can be given). When the captain doesn't make a decision or leaves this to the F/O this should be seen as a chance to improve and practice decision making. The F/O should take charge and make decisions (where appropriate) as his experience grows (don't wait for the captain to tell you how to fly the difficult approach, tell him
how you will fly it (and suck up the advice given if you miss out on something). When you improve you will generely notice that the captain will let you run the game (freeing up capacity for him to deal with whatever, or just relaxing) and when you tell him what you will do he will just replay, "ok, great or fine". When flights consistantly go along those lines, and you no longer have to seek advice from the captain (except the odd situation), you are about ready yourself.
If the F/O was just along for the ride during his career and let the captain make all the decisions, he is:
a) Not suitable for a command upgrade (ever!)
b) Not suitable as a F/O
In short. This is a craftsmanship and being a F/O is an apprenticeship to become a captain.
That is the way it SHOULD be at least...
For sure there a bad apples that slipped through the net (learn what kind of captain that you will
not be). And there are lousy F/Os who slipped in and eventually get an upgrade due to unions and seniority list etc.
And there are just plain and simple crappy outfits.
All speaking in general. As for the original poster I have no clue what advice to give. I actually don't even understand the question asked. If you are ready your ready. If not, no book or study material will help.