*Proactivity: It is something appreciated by any employer in any kind of work or position. You will never be "behind" if you are proactive. Of course, you always do things following the employer's policy.
*In addition to the training you may receive, ask for any material containing the store policy, routines, or POS system information you could keep. They are a great source of knowledge to help you speed up your learning process.
*Get yourself to practice, be curious whenever it is possible. Ask your more experienced colleagues, use your off-work hours to study about the work.
*Try to memorize the product codes! Once you memorize them, you will save much time when ringing.