After two viewings of -- and some reflection on -- X-Men: First Class, I've come to the conclusion that the moral to its story is:
"Don't be careless with your queens."
Below are my points, which are riddled with *SPOILERS*:
Dr. Klaus Schmidt (aka Sebastian Shaw, aka the Black King) is "careless" (to put it mildly) with Erik Lensherr (aka Magneto)'s queen -- his mother -- and ultimately pays for that decision with his life.
The CIA is careless with (by undervaluing and disbelieving) its queen -- Moira McTaggart -- and ends up being beguiled into placing nuclear missiles in Turkey, sparking the Cuban Missile Crisis.
Sebastian Shaw is careless with his own queen -- Emma Frost (aka The White Queen) -- by sending her on to Russia, alone and defenseless. This allows her to be taken, leaving Shaw without his greatest asset come the Battle of Cuba. This, too, costs him his life.
Professor X and Hank McCoy (aka The Beast) are both careless with their common queen -- Mystique -- by undervaluing her true worth and beauty. This allows her to be taken in by Magneto.
One could even go as far to say that society-at-large has failed the fallen and misused "Angel Salvadore" in a way that allows her to be taken in by Shaw's Hellfire Club and Brotherhood of Mutants.
The ultimate victor of X-Men: First Class is arguably Magneto, who seems to best grasp how *not* to be careless with his queens. By honoring the memory of his mother, he is empowered to ultimately avenge her murder. By honoring the undervalued Mystique and by salvaging the discarded Emma Frost, it is he who ultimately walks away with them as allies.
Likewise, Xavier is only able to be succeed in stopping the Cuban Missile Crisis (where the CIA has failed) by honoring that queen (Moira) that the CIA had themselves all but discarded. Without her discoveries, Homo sapien would have gone the way of the dinosaur, via mushroom clouds galore.
In short, undervalue and misuse your queens, you will lose. Honor and guard your queens, you will be victorious.