How do I know if my product will sell before I make it?

You find out by asking people to commit to something before it exists, in the smallest way they can, because the only signal worth trusting is somebody choosing to spend money or attention on a thing that isn't made yet. Everything else is you interviewing your own enthusiasm, and your enthusiasm gives a lovely interview.

I want to start with the feeling of certainty itself, because certainty is the trap. The idea you are most sure about is the one you check least, it never even occurs to you to check, why would it, you already know. Being sure feels exactly like being right, and I once owned an entire shelf of marked-down Liberty fabric that proves they aren't the same thing at all.

What counts as real interest, and what doesn't?

The weak signals first, the ones that feel like proof and aren't.

Likes aren't interest. A comment saying "ooh lovely" isn't either, because complimenting a photo costs the person nothing and asks nothing of them. Friends and family saying they'd buy it doesn't count, they love you, so they're answering a different question to the one you asked.

Your own certainty doesn't count, which is rather the whole point of this piece. And a competitor selling something similar is the sneaky one, because it feels like evidence. It tells you a market exists. Whether yours will land in it is a different question.

Real signals all have the same shape: the person gave something up before the thing existed. Somebody joining a waiting list for it, somebody pre-ordering it, somebody asking when it will be ready, and strongest of all, somebody asking you for it before you'd ever mentioned making it, which usually arrives disguised as a casual question in your messages.

The dividing line is what it cost them. A compliment costs nothing, an email address costs a little, a deposit costs something real. The further along that line somebody goes before the thing exists, the more their opinion is worth.

What happens if I skip the checking?

I can tell you, because I did.

I once ordered a whole batch of Liberty fabric and accessories from a supplier, completely convinced it would sell on the Liberty name alone. I didn't check with anybody. Why would I? It's Liberty, people love Liberty, I love Liberty. Checking would have felt like a waste of an afternoon, which is exactly how the trap works. The surer you are, the less you look.

It sat on the shelves for ages. Ages. In the end I marked the whole lot down just to shift it, and every markdown came straight out of margins I'd worked out properly in the first place, which stings in its own particular way.

Looking back, I'd made 2 separate mistakes.

The first is the obvious one: I never checked whether anyone actually wanted it. The name felt like validation and it wasn't, and neither was how sure I felt. My conviction was not demand, however loud it got.

The second took me longer to spot. When I did come to sell it, I described the fabric. The prints, the weight, the name, what it was. I never described what it would become in somebody's hands, the dress it could turn into, or the quilt for the new baby. People don't buy the thing, they buy what the thing turns into, and I stood there for months selling the thing.

Bulk buying is where a wrong guess gets expensive, so I'll say it plainly. A wrong guess on a single make costs you an evening and some offcuts. A wrong guess on a bulk order becomes physical. It takes up shelf space, it ties up money you needed for other things, and it looks at you every time you walk into the workroom. The size of the order should follow the size of the evidence, and a feeling is not evidence, however strong it is.

How do I test an idea before I commit to it?

In order of cost, cheapest first.

Ask the people who have already bought from you what they want next. Hardly anyone runs this test and it does my head in a bit, because those people have done the single thing that makes an opinion valuable: they've paid you once. A past buyer telling you what she wishes you made is worth more than 100 strangers being polite about a photo.

Show the work in progress and watch what people ask about rather than what they compliment. A compliment is manners, but a question usually has intent behind it. "That's gorgeous" tells you almost nothing, whereas "would you do that in green" and "how much will these be" are somebody imagining owning it, and "when will it be ready" is a hand already reaching for a purse.

Offer it made-to-order or on pre-order before you commit to stock. If people will pay for it before it exists, make it, and if nobody will, a supplier order just got cancelled before it could hurt you. This one is especially useful for seasonal collections, where the runway matters as much as the product does, because a pre-order gives you the validation and the head start in the same move.

And if none of that fits what you make, make 1 and see whether it sells before you make 12.

Now the honest bit, because validation gets talked about like a guarantee and it isn't one. Some things genuinely only sell once they exist and can be held, and no waiting list would have predicted them. You will still get it wrong sometimes, even after checking. What checking changes is the size of the wrong: 1 sample instead of a bulk order, a handful of pre-orders instead of a shelf you have to walk past every day. A smaller mistake is still a mistake, but it's one you can afford to make again.

What if I don't have anyone to ask?

Read that list of tests back, because something is hiding in it. Every genuine signal on it needs somebody who can already hear from you. Asking your buyers what they want next only works if you can reach your buyers. Showing the work in progress only works if somebody is watching. A pre-order needs a person to offer it to. Strip it back and every test is really asking whether a line exists between you and the people who might want the thing.

But have you considered what a waiting list actually is? It's the test and the launch in the same object. Announce the idea, and if 30 people put their hand up to hear when it's ready, you've got your validation and your customer list in one go, the same 30 people, already warm, already waiting. And if 3 people join, you've learned that too, for the cost of a signup form rather than a pallet of fabric.

The people who put their hand up are the people you sell it to. That sounds almost too simple, and it's the opposite of how most of us were taught, make the thing first and go looking for the buyer afterwards.

How you build that list, what you send while the product doesn't exist yet, and how a waiting list turns into a launch is more than one post can hold. I've put the starting point into a free email course called 7 Days to Shift Your Shop, one short email a day for a week, walking you through moving from making-then-hoping to asking-then-making. If you want the step-by-step, it's there.

Somewhere in your head right now is an idea you are completely sure about, and being sure feels exactly like being right. The fabric felt like that too