Experience is the best teacher and for the price it damned well better be.
Like other expensive things, you should shop around for the same value but at a lower price. With experience you need to study the experience of others. Read biographies. Pay attention to history. Talk to insightful people. Take courses.
A fox, a bear and a wolf catch three deer. They are around the carcases, congratulating themselves on their prowess. The bear asks how they should divide the deer among themselves. The wolf suggest one each. The bear kills him and eats him.
Turning to the fox, the bear asks how to divide the carcases. The fox suggests, “All for you, sir.”
The fox knows that like the pedestrian who has the right of way, trusting the rules leaves you “dead right.”
We hold the fox as the model of shrewd for a reason. If you click on the fox you will find that cunning, another fox trait, comes from the Scottish word, kennin, which means “to know”
The best form of shrewd is to know by observing others. Way cheaper than trying to make all the mistakes yourself.