The right first order depends on how you will sell the garments, how much demand you can test and how confidently you know the fit and size mix. A smaller, well-tested release can teach you more than a large order built on assumptions.
A sample, a preorder, a market stall and an online drop each create different requirements. Decide whether the first garments are for testing, selling, gifting, content or a combination of these.
Inspect the blank garment, print placement, colour and fit. A sample also gives you something real to photograph and lets you check how the design looks on the chosen garment.
Past sales, email replies, preorder interest and event attendance can inform the size mix. Do not treat likes or follows as confirmed demand.
Order quantities should account for the actual audience rather than an assumed standard. If you do not have enough information yet, keep the first range focused and use the result to improve the next size run.
A tee, hoodie or cap can share a visual language without requiring every product to launch at once. See Range / Collection Design for help shaping the product mix.
Next step: Bring your garment choices, artwork and proposed size run to Trap Door Print.