Don't sabotage a sale by your superior product knowledge.
My first sales job was at 1 800 Contacts. We had a special on contact solution along with an internal competition.
I studied the solution and pitched it to the customer. I went over the benefits, the science, the promotion, and wrapped it up with a smooth close. My sales were the worst on the team.
Confused and frustrated I went to my manager. She jumped on the phone, pitched the contact solution, and got a sale. This was her pitch:
Would you like me to throw in some contact solution, we have a good price on it right now?
Simple. Sweet. Effective.
Don't oversell your product. Don't sound desperate. Confidence and simplicity will help you win.