While reading the excellent biography of Scipio Africanus by B. H. Liddell Hart, I have been struck by the Roman general's attention to small details. He left little to chance and was able to turn seemingly small things, such as whether the Carthaginian forces arrayed against him had completed their breakfast, to an advantage.
One memorable decision: While preparing in Sicily for an invasion of north Africa, Scipio conscripts 200 Sicilian youths who are nobly born. They all bring horses and arms. At the same time, he has his officers pick the 200 most promising soldiers from a pool of Roman recruits. The Sicilians are nervous and reluctant to participate in the African invasion. Scipio tells them that he doesn't want half-hearted soldiers and so they won't have to participate provided they train the Roman conscripts in horsemanship and give them their horses and arms. The Sicilians are more than happy to do so.
Scipio winds up with 200 Roman cavalrymen at little expense.