Food has two gates before it has a price, and most mistakes are walking past one of them.
Not settling the licence question
Some foods need a licence somebody must hold, and the question is whether you hold it. Metzee cannot check that for you. Prohibited items.
Promising delivery before asking the courier
Many couriers refuse perishables outright, some restrict liquids, and transit times are not kind in an Indian summer. Ask before you quote. Packing food.
Leaving allergens out
Write them in words, not only in a photograph of the pack. A buyer searching for an allergen needs text.
Confusing best-before and use-by
One is about quality, one is about safety. A use-by date must never be passed, and saying "best before" when you mean "use by" is the error that matters most.
Posting something that must stay cold
Unless you have a cold chain you can rely on, the honest answer is shelf-stable or collection.
Relabelling somebody else's product
Never. The label is the product's identity.
Not saying how to store it
A line in the parcel — the date, how to keep it — costs nothing and prevents the complaint.
The one that costs most
Selling past a use-by date. Everything else here is a disappointed buyer. That one is not.
Questions people ask
Can I sell homemade food?
Only if you hold what the law requires for what you are doing.
Are hampers worth it?
Yes, presented well, with every date stated — not just the longest.
Is local-only a disadvantage?
For most perishables it is the only honest option.
More: selling food, describing it honestly.