In the Season 7 premiere episode of "Game of Thrones," Sansa (Sophie Turner) tells her half-brother Jon (Kit Harington) that she "learned a great deal" from Cersei Lannister (Lena Headey), after he tells her it sounds like she admires the Queen. Indeed, Sansa has spent time emulating Cersei's appearance and envying her role as Queen. But she's learned more than southern manners and dress from the ruthless Lannister, and she intends to use that knowledge to keep Winterfell safe.
Lesson 1: Keep your enemies close
In the season 7 premiere, Sansa reminds Jon that he's been so preoccupied with the Night King that he's forgotten about their many enemies to the South, most notably the Lannisters. This is echoed in Cersei's monologue to Jaime in the same episode, when she's outlining all of their enemies to the East, West, North and South.
Lesson 2: Get revenge
In the penultimate episode of season 6, Sansa is finally able to exact revenge on Ramsay Bolton (Iwan Rheon) by feeding him to his beloved hounds. This parallels Cersei's revenge on Septa Unella (aka the Shame Nun).
Lesson 3: Use getting underestimated to your advantage
Cersei's been fighting her whole life to be just as recognized as the boys, and while Sansa begins the series embracing the fact that she's destined to grow up just to marry, all that changes when she's in King's Landing and around Cersei full-time. Not only does she see the reality of what it would mean to marry Joffrey, but she sees Cersei's manipulation in action. By the time she's back at Winterfell, she knows she's way more than a pretty face.
Lesson 4: Reward those who are loyal to you
In the Season 7 premiere, Sansa urges Jon to reward the families who fought for him at the Battle of the Bastards with the castles of the Karstarks and Umbers, families who betrayed him. Jon didn't take her advice, so we'll see how that pans out. But it's likely that idea was gleaned from Cersei, who is constantly promising rewards to those who help her. Qyburn, for example, is elevated to trusted advisor after he gets to King's Landing and helps Cersei in her various plots.
Lesson 5: Trust no one
Finally, Sansa has learned not to trust anyone--even her brother Jon. He has to remind her that they must be on the same side to survive. Sansa is smart to be very weary of Littlefinger (Aiden Gillen), though. Cersei doesn't trust anybody, and tells Joffrey early on that anyone who "isn't us" is the enemy.