It's hard to find good talent these days but it's also the case that employers have many applicants to choose from. Here are some basic skills, traits and abilities that I would look for and train on if I were hiring and managing retail sales help. This list applies to restaurant employees as well.

Offer eye contact! The customer may not return or initiate eye contact but your lack of offering it indicates a lack of your interest and presence in serving the customer and doing an effective job.

Listen! Listen to the customer. No, I mean literally listen to the customer. Many errors in sales and service are the result of sales people simply not hearing the customer. If you cannot hear normal speech in your work/sales environment call it to the attention of your management. If the music is too loud, the sound system not adequate, background noise too loud or distracting suggest ways to change or improve your listening environment. If the customers feel they can't be heard they will go and buy where they feel they can be heard. (Note to management: for telephone and listening dependant roles (i.e. drive through windows) please ensure that sales people speak and understand English (in the US) clearly.)

Understand the difference between urgent and important. A ringing phone is urgent but answering a caller's question is seldom more important then serving the customer and the sale present before you. In businesses where telephone sales are important sales staff and systems should be set up to serve both efficiently and separately.

Develop an authentic presence. Understand that your entire demeanor reflects both positively and negatively on the business. Be neither grumpy nor overly perky. Develop a persona that presents you and the business you represent in the best light. Intelligent, knowledgeable, capable, friendly, helpful, etc. these are the most desirable qualities in a retail clerk.

Know your product and your store. Take time to know what products you are carrying, where they are in the store, and enough about them to be knowledgeable and helpful when customers ask questions. If you don't know the answers know who does and get the answer for your customer.