Does Athena appear to have her plan all figured out or does she seem to improvise as she goes?

Athena is a champion of Odysseus throughout Homer's Odyssey. She feels a special affinity for him, as Athena is the goddess of wisdom, and Odysseus, though mortal, is renowned for his cunning and cleverness. Though Athena is a shrewd engineer of the social interactions of Odysseus and his companions, she is nonetheless at the mercy of other gods (chiefly, Zeus). In the Odyssey's opening book, Athena approaches Zeus and asks the king of the gods to intervene to help Odysseus ("But my heart is torn for wise Ulysses, unfortunate man, who far from his friends has long been suffering afflictions" [1.45]). Zeus assures her that it is not he who holds a grudge against Odysseus, but Poseidon (whose favored Cyclops Odysseus had blinded). Zeus encourages Athena: "Let us who are here all take thought of [Odysseus's] return, that he may come home" (1.78).
From this point forward, Athena navigates the mortal world at will. On one occasion, she appears to Telemachus (Odysseus's son) as a stranger ("Mentes") to encourage him to set sail after his missing father. Shortly thereafter, she assumes the guise of Telemachus himself in order to recruit a sailing crew. She also provides the crew with fair winds. Nor are her entanglements only with Telemachus—she enters the mind of a young princess, Nausikaa, in Book 6, and inspires her to go wash her clothing in the sea, where she (not coincidentally) encounters Odysseus (whom Athena made to appear especially tall and handsome). A final—and especially gruesome—feat of Athena's is her engineering of the death of Penelope's suitors. At the epic's close, Athena convinces the citizens of Ithaca to forgive Odysseus for the death of the suitors and accept his return to Ithaca.
Athena's behavior is largely unbridled. That said, she is restrained only by the whims of other gods (Zeus and Poseidon). It is a common dynamic in classical literature, whereby the gods are not devoid of human characteristics (competition, jealousy, pride), though their world is apart from and superior to the mortal one.

Athena does have a plan figured out. If you think about it, Athena is a goddess, and according to most people's beliefs, gods and goddesses always have a plan in place. She also always seems to be one step ahead of Odysseus, which helps us see that she does, in fact, have a plan in place.
She also always seems to show up at the right time—when Odysseus seems to be "in over his head." She then helps provide him with the tools necessary to get himself out of the trouble that he is in. Overall it seems like Athena lets Odysseus try to solve things on his own at first but will then intervene when it is appropriate.