Quite simply, get Good at it. For sales confidence, work on getting better at sales.
In sales, the 4 parts are as follows: Prospecting, Presenting, Proposing, Closing.
Get good at Prospecting - it's where all of it starts.
Ask better Questions. Listen harder.
Get good at Presenting. In Hugh MacLeod's Authenticity is the new Bullshit, Hugh points out that the best in their field are great presenters. (Think TED talks or Jobs.)
In Nic Bates' blog today,
I paraphrase, "Get good at something. It builds Confidence. Confidence is contagious. Like Enthusiasm."
Stop Sucking at Sales!