Before you begin to write a sentence, imagine the scene you want to paint with your words. Imagine that you are the character and feel what the character feels. Smell what the character smells, and hear with that character’s ears. For an instant, before you begin to write, see and feel what you want the reader to see and feel.
And what, you ask, does writing teach us? First and foremost, it reminds us that we are alive and that it is a gift and a privilege, not a right. We must earn life once it has been awarded us. Life asks for rewards back because it has favored us with animation. So while our art cannot, as we wish it could, save us from wars, privation, envy, greed, old age, or death, it can revitalize us amidst it all.
It is absurd to think that the only way to tell if a poem is lasting is to wait and see if it lasts. The right reader of a good poem can tell the moment it strikes him that he has taken an immortal wound - that he will never get over it.