1. Never, ever, ever lie to your customer. This is the first and fore most rule to apply in business.
2. Never act like you know something when you do not. It is always better to tell a customer that you can find out and get back with them than it is to tell then something that is incorrect.
3. Never exaggerate the usefulness of something. If you just tell it like it is, some people will like it just that way. Not everyone is going to want what you have to sell.
4. Always do what you say you will do. If you tell someone you will get back with them, than do it. If you say you will take care of something be sure to do that too.
5. Always be sincere. If you are not really interested in people and their best interest they can feel it and detect it. If you smile and mean it you will be much more appealing to them.
6. Do not focus on what is in it for you but instead think about whether it is right for the customer. If they do not perceive value to them then you probably do not want them to buy your product anyway because they will likely be unhappy customers.
7. Tell them if you do not think it is right for them and why, if they still want the product then fine but you must be honest.
8. If you see something wrong with their thinking about the product or service point it out. Sometimes people misunderstood what they are told and if this happens it usually will come back on the salesperson. Be sure they understand what they are receiving.
9. Never over sell. You are not going to force someone to buy something if they really do not need or want it. Over selling seems desperate and you might chase off what otherwise might have been a buying customer.
10. Always consider if they would come back to you to buy again. Repeat business is a huge factor in building your business. If you treat someone badly chances are they will not be your future customer.
11. Always be fair with people and it will come back to you two fold.
I have always looked at the sales and marketing business as an opportunity to provide a service to people. I have found that most people appreciate receiving the facts but making their own decision. They are typically just interested in your knowledge and correctness on the subject. If you can provide this with integrity and credibility you are ahead of the game!