It's not quite true that a great salesperson can sell any anyone. For a start they might not need it-and sales is all about meeting needs. However, selling is one of those things that can happen to anyone, no matter what their job description, so here are the basics.
Step 1 Build trust
You need to establish trust with the person to whom you are selling. They don't have to be your best friend but essentially people don't buy from people they hate or distrust.
Step 2 Don't misunderstand the customer
Understand the needs of the other person. Then it's up to the that the benefits of their goods or salesperson to demonstrate that the benefits of their goods or services match the requirements. Without that, you have no sale.
Step 3 Ask clever questions
Ask questions to find out what the customer's problems and issues are. Then think through what the needs must be. It's often more effective then asking the obvious, 'What do often more you need?