The first thing worth saying about a first convention is that most people there are not in costume. Cosplay is the visible part, and it is a minority of any show floor. Turning up in normal clothes is normal.
The second thing is that a convention is a physical endurance event disguised as a social one. Ten to twelve hours on concrete, largely standing, in a hall with the air conditioning fighting several thousand people and losing. Almost every piece of advice below follows from that.
Footwear is the entire decision
If you get one thing right, make it this. Convention floors are concrete under thin carpet, and you will walk five to eight miles without noticing you are doing it, most of it in queues where you are standing still — which is harder on feet than walking.
Wear shoes you have already worn for a full day. Not new ones, not ones you think will be fine. Cushioned soles, broken in, with socks that will not slide. This is the single most common first-convention regret and it is completely avoidable.
If you are cosplaying in footwear that is part of the costume, bring real shoes in your bag and change into the costume shoes for photographs. Everyone experienced does this.
Layers, because the building cannot decide
Convention centres run cold in the morning, hot by mid-afternoon in the dealer hall, and cold again in panel rooms. A t-shirt with a light hoodie or overshirt handles all three, and the layer you remove can go in your bag or round your waist.
Avoid anything you cannot take off. A heavy sweatshirt in a crowded dealer hall in the afternoon is genuinely unpleasant and you will end up carrying it anyway.
Outdoors matters more than people expect, too. Queues for badge collection and for the big panels form outside the building, sometimes for an hour, in whatever weather the city has that day. Check the forecast for standing still, not for walking.
The bag matters more than you think
You will be carrying more at the end of the day than the start — prints, merchandise, a programme, water. A tote is the standard for a reason: it is flat against your body in a crowd, it holds a poster tube diagonally, and it weighs nothing empty.
A backpack holds more and distributes weight better, at the cost of being the thing that hits three people every time you turn round in a crowded aisle. If you bring one, take it off and hold it at your feet in queues and panels. People notice, and they appreciate it.
What actually needs to be in it: a water bottle, a portable battery and cable, whatever cash you plan to spend, hand sanitiser, painkillers, and a snack. The battery is not optional — conventions destroy phone batteries through constant poor signal and camera use, and the queue for a public charger is long.
Two more that experienced attendees carry and first-timers do not: blister plasters, applied before you feel the blister rather than after, and deodorant. Neither is glamorous. A crowded hall in hour eight is a shared environment and the people who plan for it are doing everyone a kindness, themselves included.
What to wear if you want to look like you belong
The unofficial uniform of the non-cosplaying attendee is a graphic tee, comfortable trousers, and good shoes. That is genuinely it.
The tee is where the personality goes, and there is a real advantage to wearing something that is not the show everyone else is wearing. A design built on the aesthetic rather than a specific series starts more conversations, because it does not sort people into "watched it" and "did not". Kanji, traditional patterns, folklore imagery — people ask about those.
Dark colours hide the inevitable. Convention food is eaten standing up.
Multi-day shows
A three-day convention is not one long day repeated. It is a resource management problem.
Plan a shirt per day and pack them the night before rather than deciding each morning, because mornings at a convention are always more rushed than you expect. Trousers can repeat; shirts should not. If you are cosplaying at all, do it on one day rather than all three — almost everyone who tries to sustain a costume across a whole weekend is out of it by day three anyway.
Build in one deliberately quiet block per day. Not a rest when you are exhausted, but a scheduled forty minutes sitting down somewhere away from the hall. It is the difference between enjoying Sunday and enduring it.
The badge, and other small logistics
You will wear the badge all weekend, so put it on a lanyard that does not saw at your neck, and consider that it appears in every photograph you are in. Badge collection is almost always faster on the first morning than the evening before, or the reverse, depending on the show — check which, because it is routinely an hour's difference.
Keep the badge somewhere it cannot fall out, and photograph it. Replacing a lost badge ranges from irritating to impossible.
If you want to try cosplay without committing
Closet cosplay — assembling a recognisable look from clothes you own plus one or two bought pieces — is how most people start, and nobody will think less of it. A single strong accessory does most of the work.
A mask worn on the side of the head is a well-established convention look that costs nothing in comfort and reads as deliberate. Kitsune masks in particular sit in an unusual position: they are recognisable to the audience without being from any one series, so they work as costume, accessory or plain decoration.
Two practical notes. Anything that obscures your face has to come off for badge checks and security, so plan for that. And prop weapons are governed by rules that differ at every single convention and are enforced strictly — read that page on the event's site before you build anything, not after.
Photograph etiquette, in one paragraph
Ask before photographing anyone in costume, every time, and accept no gracefully. Do not touch a costume or its wearer. If someone is eating, sitting on the floor, or visibly on a break, they are off duty — let them be. And if you are the one being asked, you are allowed to decline; the convention norm is entirely on your side.
Money, and the artist alley
Decide your spending number before you go in, because the dealer hall is designed to make that decision for you. Walk the whole alley once without buying anything, then go back for the two or three things you are still thinking about. Almost everyone who buys on the first pass regrets at least one of them.
Carry cash. Artist alley card readers depend on the same overloaded signal as your phone, and the artist eats the fee either way.
Things first-timers consistently forget
Eat before the queue, not after. Convention food is expensive, slow, and timed exactly opposite to when you have a gap.
Fill your water bottle at the fountains. Dehydration is what turns hour eight into a headache, and hall air is bone dry.
Bring a poster tube or buy one early. Print artists sell out of tubes long before they sell out of prints, and a rolled print in a tote does not survive the day.
Find the quiet room on the map. Most large conventions have one. Knowing where it is before you need it is worth the thirty seconds.
Take the badge photo seriously. You will be wearing it in every photograph you appear in all weekend.
Dressing for the specific thing you are doing
A convention is several different environments in one building, and they have different requirements.
Panels mean sitting on a hard chair in a cold room for an hour, often after queueing outside it. This is where the extra layer earns its place, and where a backpack becomes a nuisance to everyone in your row.
The dealer hall is the hottest part of the building and the most crowded. Go in your lightest layer, keep your bag in front of you, and be aware that anything hanging off it — a strap, a keychain, a prop — will catch on a stall.
Photoshoots and gathering spots tend to be outdoors or in a lobby, so whatever looks best is also whatever you are coldest in. This is the one time it is worth carrying the jacket rather than wearing it.
Concerts and evening events are standing, dense and loud. Flat shoes, nothing you would mind having stood on, and earplugs if you are sensitive — a surprising number of regulars carry them.
Glasses, hair and small annoyances
Contact lenses in a dry convention hall are considerably less comfortable than they are at home, and the air handling in these buildings is aggressive. If you wear both, glasses are usually the better call for a long day, unless a costume rules them out.
Long hair is worth tying back for the dealer hall regardless of how it looks, purely because of how many people are moving past you at close range. Wigs need a wig cap and more pins than you think, and they are hot — another argument for cosplaying on one day rather than three.
Getting there
If you are travelling, pack the costume in hand luggage or carry it, never in a hold bag. Lost luggage that turns up on Sunday has cost you the weekend, and this happens to somebody at every show.
Wear comfortable clothes to travel in and change at the venue if you must. A three-hour train in full costume is a bad start to a long day, and most large conventions have somewhere to change.
The packing list, condensed
Worn: broken-in shoes, socks that do not slide, a shirt you like, a removable layer.
Carried: water bottle, portable battery and cable, cash, hand sanitiser, painkillers, blister plasters, deodorant, a snack, a poster tube if you plan to buy prints.
Left at home: anything new, anything you cannot take off, anything you would be upset to have stepped on.
Afterwards
Expect to be wrecked. "Con crud" is a real and thoroughly documented phenomenon — thousands of people from everywhere, indoors, for three days, sleeping badly. Sleep, water, and not scheduling anything demanding for the Monday is most of the cure. Wash the tote.
Last thing
Nobody is assessing your outfit. The overwhelming majority of people at a convention are delighted that other people turned up at all, and the social floor is far lower than a first-timer expects. Comfortable shoes, a shirt you like, a bag that holds what you buy. That is the whole brief.