Most of us forget the basics and wonder why the specifics don't work.
It does not matter how smart you are if nobody knows what you are talking about.
People buy from people they trust and they trust people they like.
People buy-into what they can understand quickly. If it takes you a long time to make your point, most people think you don't have one!
Fear is a survival tool not a handicap.
Don't let the opinions of others define who you are. Take them into consideration, make adjustments if necessary and then go be you!