In order to make any sale,the person you are trying to sell to must see the benefit of what you are recommending. Your customer must see that you are trying to help them, rather than just sell them something.
Each of knows the reasons "why" we recommend a timing belt or a wheel alignment. But, sometimes in the mist of a busy day we don't effectively communicate the "why". When a customer understands that replacing the timing belt is thousands of dollars less than major engine repair, the customer knows the why. The customer sees that you are trying to help.
The other component in selling is clearly identifying your true profile customer, and ones that you have established strong relationships with. You will have an easier time selling to the right customer and those you have created strong relationships with. Focus on these customers and do all you can to continue to identify and build more of these relationships with the right customers.
I am not saying to ignore certain customers, but the truth is we cannot be everything to everyone and attempting to be will eventually hurt sales, morale and profits.