Briefing a packaging project without knowing print
You do not need to know what flexo is. You need to know four things and let the specification follow from them.
You do not need to know what flexo is. You do not need to know FOGRA39 from PSO Uncoated, or what a litho-laminated carton is, or why foil tooling costs the same for fifty units as for fifty thousand. A designer and a printer between them know all of that. What you need to know is four things, and the specification follows from them.
Name the container
A folding carton, a label on a jar, a pouch, a bottle, a can, a tube, a mailer box, or a set of several. This one choice decides whether a dieline is needed, whether the artwork wraps around a curve, whether distortion has to be compensated for at the shoulder of a tube, and whether a structural supplier should be involved before the design starts. It is the packaging equivalent of choosing the platform for a video, and it removes more questions than any other.
Say whether a dieline exists
A dieline is the flat shape of the pack before it is folded. Nothing can be designed for a carton or a pouch until it exists. Either you have it, your supplier provides it, or someone has to create it, and "I don't know" is the most common honest answer. Say which. The two answers that mean artwork cannot start yet, "no" and "I don't know", are the single most common cause of a packaging delay, and saying them in the brief is what turns a delay into a plan.
Give the quantity as a range
Under a hundred, a few hundred, a few thousand, tens of thousands. That is enough. From the range a designer knows whether this is digital or offset, whether Pantone spot colours are economic, whether foil or embossing make sense, what the colour profile should be, and how many working days the press needs. You are not being asked to know any of that. You are being asked for a number you already have.
Give the date the product is on the shelf
Not the date you think the artwork is due; the date the pack is needed in the world. A designer works backwards from it: shipping to the warehouse, print lead time, a legal review if there is a regulatory panel. The gap between the shelf date and the real artwork deadline is routinely six weeks, and briefers who guess the artwork date guess it late. Give the shelf date and let the subtraction be done for you.
List the regulatory content
Barcodes, ingredients, nutrition, allergens, recycling marks, net weight, country of origin, batch fields, warnings. Tick what applies. A legal panel then gets reserved at the mandatory minimum type size, a legal review gets its ten working days in the schedule, and the question of who supplies the text gets asked while there is still time to answer it. Missing regulatory content is the second most common cause of a packaging reprint, after dielines.
The one thing to check before any of this
That your logo exists as vector artwork. A logo that lives only as a JPEG on the website cannot be printed at packaging quality, and this is discovered late almost every time. If you are not sure, ask whoever made the logo for the files, before you brief anything.