This afternoon, a sales person knocked at my door, wanted to promote their product ... a multi-purpose vacuum cleaner. She did a demo but in the end, I did not buy.
Many people make the mistakes of trying to sell their products or services before fully understanding their prospects' most pressing challenges.
This is similar to your doctor handing you a prescription before taking the time to fully understand your symptoms.
It's the same logic!
You would not promote your products and services to customers before you have a clear idea of what they need and what their problems really are.
Before you try to sell anything to your customer, find out first what he needs.