Not only do you become familiar with the location of all the items you need, but you can become familiar with the store's personnel. If you are only shopping for prepackaged food, you can really move through the supermarket, but if you have to inspect produce or meats or fish, the time you spend is going to be greatly increased. You may also want to consider shopping in stores other than supermarkets. Customers may want you to stop by the liquor store, deli or carry-out. You may wish to increase your fees for this additional service or charge the same as for groceries.
Organizational ability is the key to a successful grocery shopping service.
It is a challenge to keep orders straight since you will probably be shopping for several accounts at once. As time goes by, you will discover ways to make this easier, but you may wish to use two carts and put hand held baskets into the carts to create separations. Of course, the cashier must ring each order separately in order to provide receipts for each of your clients. Remember, in any service organization, you are selling yourself, as much as you are selling your product. Courtesy, punctually, and a big smile can take you a long way down the road to success.