An expert is...

A good teacher or an expert is someone who, after listening to you for five seconds, knows :

• what you know,
• what you don't know,
• what you want to know, and
• what you need to know in order to achieve what you want to know.

Otherwise both of you will be spending unproductive hours going around each other repeatedly.  I am sure you have see this only too often, where two parties confuse each other out on different frequencies.

Hence, if you are offering advice, do take a step back and spend five seconds to figure out what they other person knows, does not know, wants to know, and what he needs to know.