What does the customer what to know?
Then make a list for each product.
The customer wants to know (in no particular order)...
- How much does it cost?
- Where was it made?
- What materials is it made out of?
- Why it will solve her problem?
- What makes it different from all the others in its category?
- How long will it last?
- What other options and accessories are available?
- How soon can she have it?
- Will she have to put it together?
- Why should she buy it from you?
Make a sheet that answers all those questions for everything you sell and your staff will have the product knowledge they need.
PS The hard part is getting to know the customer well enough to be able to answer the right unspoken question. Which one of those questions is the most important to her? Answer that one first and you have a far better shot at making the sale.