Dark times reign in Westeros, and chaos has gripped the land from Winterfell to King's Landing and beyond. We, the people of Westeros, see only the grimmest of hopes for a peaceful resolution, especially after the (spoiler alert) destruction of the Great Sept in King's Landing, as well as the bloodshed outside of Winterfell in battle between Jon Snow's beleaguered forces and Ramsay Bolton's troops. 

Despite the infighting and with the forthcoming appearance of Daenerys Targaryen on Westeros' shores, with her dragons and armies, a threat unlike any other looms North of the Wall, in the form of thousands of White Walkers. 
These White Walkers answer to no human lord and present a threat to the entire kingdom. 
Therefore, as we would for any enterprise or team that is faced with a challenge (even one so insurmountable as a horde of undead ice demons), we have taken it upon ourselves to humbly (and, given some of the violence that has reigned over the kingdom at your hands, with no small degree of a plea for mercy) put forth recommendations for the key members of Westeros' ruling families, so that they may work in greater unity and with enhanced success as a team. 
To that end, we have put together a Teamwork Tool discussion, complete with Culture Profiles, for, in no particular order and betraying no preferences, Daenerys Targaryen, Jon Snow, Tyrion Lannister, Sansa Stark and Cersei Lannister.
The eight dimensions of culture, as defined by RW-3 CultureWizard's Culture Calculator, are Hierarchy, Communication, Control, Time, Relationships, Group, Motivation and Formality. Though we will not show every aspect of each member's culture profile, we will highlight a few, particularly though which we believe are causing difficulties for these five individuals to come together and work as one against the threat.
The first dimension we will consider is that of Hierarchy. Some of you fair lords and ladies are hierarchical by nature, whereas others among you are egalitarian. Cersei Lannister, for instance, who, by virtue of being a Lannister, seemingly bows to no one and instead expects others to show her respect due to her position, is someone who is very hierarchical by nature. As Queen Mother of Westeros, she shows traits that clearly demonstrate her lack of desire to let others lead or show initiative, as well as her penchant for centralizing authority.
Daenerys Targaryen, however, demonstrates highly egalitarian tendencies. We see this when she frequently asks for the advice of her councilors and even in her actions to free slaves. Throughout her campaign in the east, she has not used the power vested in her by the dragons as a reason to demand respect from anyone, opting instead to prove her valor through deeds. 
It would do Daenerys well to acknowledge that with the challenges at hand, there are some structures in Westeros that simply won't yield to meritocracies, not least of them the Iron Throne. Cersei, for her part, would do well to let go of the firm grip that she has on King's Landing and accept some assistance (and initiative) from her otherwise cowed underlings. 
Communication is another weak point for this group. On the one hand are folks like Jon Snow (pretty plain-spoken for a man who came back from the dead) and Daenerys Targaryen (the whole 'breaking' the Iron Throne bit is as direct as it gets), and on the other are the Lannisters (both Cersei and Tyrion), who, to the ears of everyone else in Westeros seem to speak in riddles and who never mean what they say.  Sansa Stark could play a fundamental role here since she has a foot in both camps. Almost a queen and having suffered through quite a bit of indirectness at King's Landing, Sansa is no stranger to speaking in riddles, but she can often be plainspoken and simple in her speech, as are most of the northerners. There's an opportunity for her to act as a translator in the alliance that would save Westeros against the White Walkers (though we know there won't be any alliance, for that wouldn't make for good television...).
With this particular group, though, one dimension is more relevant than all others, and that's Motivation. Are they driven by a lust for career growth (in this case becoming king or queen) or by living a well-balanced life? Well, it's not called Game of Thrones for nothing, and Cersei, above all else, is defined by her thirst for power (er, sorry, career growth).  The same is true for Daenerys, though it's a bit more tempered, and even for Sansa, who was somewhat responsible for everyone going to King's Landing in the first place.  
Jon Snow, on the other hand, is not motivated by power but rather by his quest for peace (which is what passes for a balanced lifestyle in these parts), and the same may be said of Tyrion, who really didn't abuse his power during his brief tenure as King's Hand. 
Normally, we'd have advice on setting policies that cater to both sides and play to the common grounds, but with this particular cast of characters, it's pretty clear that the drive for power and station is a bit over-the-top and our usual suggestions simply won't work.
So what is the best course of action for success?  Team work. Jon Snow would need to be able to combine forces with Tyrion Lannister, both of whom are very moderate on the Motivation tool, and with Daenerys, who is also moderate (given the circumstances). Sansa, on the the other hand, has betrayed a predisposition for power before, but that is highly tempered by a moderately egalitarian style that would easily enable her to work together with the others. 
There's still not much one can say about Cersei but it's possible that an alliance between the other four characters would be enough to dissuade her to go along with them. If she's able to see an opportunity for self-advancement through such a policy, and it's possible that in her mind, survival against the White Walkers would trump her ambition for power, then she may work with the others to defeat the existential threat facing Westeros.
What happens once that's over, though, is anyone's guess!