Learning from a book

I remember reading a book titled “Sun Tzu- strategies for selling” by Gerald and Steven . Few things which I learned/observed from this book are as under:-

a. That selling is a trade for the ignorant and a science for the professional. Professional skills are honed through study and practice. People who think that their skills are naturally born will not focus on self improvement and their personal growth will be stalled.
b. Instead of saying “How much do you want to pay?” it’s better to say “How much are you thinking of investing?”
c. Learn from experience of others as well as from your own.
d. Strategy is an idea seeking its means of execution. Tactics are the means of execution used to carry out ideas.
e. To subdue an enemy without fighting is the supreme excellence.
f. The best policy is to attack the strategy of your enemy next best is to disrupt his alliances through diplomatic means next best is to attack the enemy in the field and the worst is to attack walled cities.
g. Ask such questions if you have lost a sale “Just for my information would you mind telling me what I/we did wrong?”
h. One should use normal force to engage and the extraordinary to win.