Staff apparel looks like the simplest part of an event merchandise order and reliably becomes the most chaotic, because it is the only part with a per-person requirement.
Count roles, not people
Booth staff, registration, production crew, VIP hosts, security and speakers often need different garments — different colors, different formality, sometimes different visibility requirements. Start from the roles and how many are in each, not from a headcount.
Get sizes early and expect them to be wrong
Sizes arrive late, incompletely, and with a percentage that turn out to be wrong on the day. Order a size buffer, particularly at the ends of the range, and accept it as a cost of doing the thing properly.
Pack by role and size, labeled
This is the detail that decides whether move-in is calm. Cartons labeled by role and size mean each team collects its own. One mixed pallet means somebody sorting garments on a floor while everything else is happening.
Everyone needs more than one
A multi-day event on a show floor is physical work. One shirt per person per day is the honest number, and it is the calculation most often skipped.
Decide what identifies a role
If attendees need to find help, roles have to be distinguishable at a glance — color, a printed role name, or a lanyard. That is a design decision worth making deliberately rather than discovering on site.
Undated apparel is next event's apparel
Printing the event name and year on staff shirts guarantees a write-off. Branded but undated apparel goes back into stock and comes out again at the next show.
Event programs covers apparel packed by role and size, and warehousing covers holding it between shows.