Error-free picking: how to prepare orders quickly and never ship the wrong parcel

Order preparation —picking— is the part of online retail the customer does not see until it fails. And when it fails, it is very expensive: a wrong order means reshipping, collecting the wrong product, customer service time, sometimes a product that comes back damaged and, frequently, a bad review. On many orders, that cost exceeds the entire margin the sale left.

The good news is that almost all mistakes have the same cause: relying on the memory of whoever is picking. What follows is how to replace that memory with a system.

1. Each product, one location

Without locations, the warehouse works as long as the same person runs it. With locations, anyone can prepare an order on their first day.

• Use a simple, consistent code: aisle – bay – level – slot (for example, B-03-2-04).
• Physically label each slot with its code.
• Record the location on each product's page (or each combination's, if sizes and colours are in different places).
• When a product moves, it is changed in the system at that moment, not “later”.

2. Place items according to what sells most

Apply an ABC analysis to the warehouse: the products that move most (A) go close to the packing area and at hand height; the ones that move least (C), at the back and on the higher levels. This alone greatly reduces walking, which accounts for most of the picking time.

3. Choose the picking method according to your volume

In a store going from 20 to 80 orders a day, switching from “order by order” to “waves” is usually the biggest productivity leap it can make.

4. An ordered route

The pick list must come out sorted by location, in the direction the warehouse is walked, and not in the order the customer added the products to the cart. It seems like a detail, but it avoids going back again and again.

5. Verify, do not trust

The definitive leap in quality is verifying with a scanner (or with the phone's camera):

• When picking: the product's barcode is scanned; if it is not the one on the line, the system warns you.
• When packing: you check that all lines and units are there before closing the box.
• When labelling: you check that the shipping label matches the order in that box.

This last point avoids the most expensive mistake of all: the swapped label. Two orders are prepared correctly, but the labels are swapped when sticking them on. Both customers receive each other's parcel. Scanning the label and the order together before closing eliminates it completely.

6. A picking sheet that really helps

• Location, reference, name, combination and units, in that order.
• Quantities other than 1 clearly highlighted: the “I put one in and it was two” mistake is one of the most frequent.
• The customer's notes and gifts or samples visible, not hidden at the end.
• For dated products, which batch to take.

7. Measure to improve

• Error rate: orders with a picking incident / orders shipped. A reasonable target is to be well below 1%.
• Lines picked per hour: tells you whether changes of location or method are working.
• Order-to-shipment time and meeting the cut-off time (“orders before 13:00 ship today”).

And record the cause of each mistake. If almost all of them come from the same two products, the solution is to move them or label them better, not to ask the team for more attention.

8. Knowing what comes in, as it happens

A notification on your phone when an order comes in —with its products— lets you plan the waves, bring forward the preparation of urgent orders and spot an odd order immediately (a disproportionate quantity, a suspicious address) before it leaves the warehouse.

In PrestaShop

PrestaShop knows what needs to be shipped, but not how to prepare it: it has no slot locations, no lists sorted by route and no scan verification. All of this can be added with a picking module that uses the phone as a scanner, so that the warehouse works the same whoever runs it.