Welcome, snikki! You've chosen a great topic in which to announce your arrival. I probably have made over twenty posts in this thread already, so I won't waste space by reiterating myself... too much.
Let me say that Cersei's instincts are usually correct, it's her intepretation of the situation or her application of tactics that are usually incorrect. She correctly sees threats and potential threats in Jon Arryn, Eddard, Barristan, Stannis, Renly, Tyrion, Margaery, Olenna, Bronn, etc. But she often misunderstands the action needed to remove threats. She sees herself as more restrained than Jaime, yet she's very oportunistic when the opportunity arises. It's the long term planning of which she's incapable. As a child, Cersei murdered her friend in a well. With just a look, she let Pycelle know to make sure Jon Arryn did not recover. She kept Robert inebriated long enough to kill himself. In a week, she built a secret coalition to defy Eddard.
But she misunderstood the timing and handling of Barristan. She's misunderstood Middlefinger's motives. She almost prevented Tyrion and Tywin from saving KL. She's botched the timing on Margaery. She's underestimated both the Iron Bank and the Faith. She's overestimated her agents' abilities to deal with Bronn and the Sparrows.
She knows the valonqar and the younger queen are coming for her. But she'll either over estimate her agents, underestimate her enemies, or misinterpret the threats entirely.
As per my other posts, I contend that the most likely candidates for valonqar are Jaime, Aegon, Jon, and Dany. Tyrion is still a candidate, but less likely. Dany could double as the valonqar and the younger queen. She might be the first head, AA, and TPTWP as well.