No thought should be required for a customer to use your solution. It should be intuitive and satisfy the principle of least surprise.
What a user naturally expects something to do — that is what it should do. Don’t make them think about it, think about why is this different, what are they doing wrong.
This is not to say that a customer should never have to think about what they are doing. It has more to do with the concept that they should not have to think about how to use your solution. It should conform to their expectations.
Of course, this requires an intimate knowledge of the cultural thought environment of your customers. You must understand what will trip up your customer, what will make them think twice about their user experience interaction.
Can I make this a more dead-simple, no-thought-required interaction? Is this the least surprising solution? What can I do to lessen the cognitive requirements of using the solution?