Inspired by the last post I got it in my mind to list some big no-nos of cosplaying. Most people who make these mistakes don't exactly mean anything bad, but that doesn't mean that the result would always be positive.
1) Respect the cosplayer
* Don't creep-sneak a photo of anyone. No matter how short someone's skirt is it doesn't give you permission to secretly try to get a photo of their panties.
* Don't take a secret photo, even if it's completely innocent. The cosplayer will not be at their best and that's not what you want either. Most cosplayers are totally fine with you taking their photo, so ask them for permission first and give them a chance to f.x. straighten out their outfit, let someone else hold their extra bags, pose in character for you - the resulting photo will be a billion times better.
* If the cosplayer says no to photos, that's a no, do not take that photo. It may seem illogical to you but there most likely is a valid reason behind the denial, they're not just refusing out of spite.
* Don't bother people needlessly: if they're eating, let them finish eating first. If they're busy, find them again later on or curse your bad luck and move on. If you want to be in the photo with them discuss it with them first.
* Never begin any kind of role play without first asking the other one's permission. You may be dressed up as Prussia but that doesn't give you any right of invading a random Austria's vital regions. In fact, don't grope people, it's sexual harassment no matter what and chances are a total stranger is not going to appreciate your hands on their genitals. You may be facing some harsh words, their fist, the security throwing you out and possibly the police, in any combination.
* No, don't even hug anyone without their permission. It's scary. The less the cosplayer is wearing and/or the bigger the age gap between you and them the more important this part is, especially if you're not looking forward to getting sued for sexual harassment.
* The cosplayer is NOT the character. Do not call them names based on the character, no matter how much you hate said character. Don't harass them, don't bully them, don't say mean things about their cosplay or their looks, and never expect them to be ok with something just because the character they're cosplaying is ok with it. Don't assault anyone - hitting someone with a yaoi/yuri paddle without consent counts as assault btw.
2) Respect the cosplayer's outfit
* It's more than likely that making that outfit has taken a long time and the cosplayer's blood, sweat and tears. Do not do anything that might damage their outfit.
* NO GLOMPING (= tackle hugging). It's not cute and never was cute. It may destroy the other one's outfit or even cause injury. Be especially careful around cosplayers that are a) much smaller than you and/or b) in cosplay that compromises their balance (high heels, heavy construction on one side etc.).
* If you're wearing face- or bodypaint, rethink whether it's a good idea to go hugging someone. Even if you sealed the paint well there's still a good chance it will rub off on the other one's clothes and cosplay outfits can be near impossible to wash.
* Definitely no destroying someone's outfit deliberately. This should be obvious.
* Also no pulling off bits of someone's outfit. They have a mask? Let them keep it. Someone in the series once pulled their trousers down? DO NOT EVEN THINK OF IT.
* In fact, don't even touch that outfit or the props included without the cosplayer's permission. There may be a reason why they're holding something just so, there may be parts that break easily - if you ask them first and they say yes they can also tell you what to look out for.
3) Respect the other people
* This is for the cosplayers to take notice of: there are other people around you and you have to take them into account.
* Don't bring anything dangerous, large props can accidentally injure someone, same obviously goes for firearms, poisonous substances and sharp blades. If you're asked to remove something by the staff, do it without complaints.
* Respect the other people's right to not have to look at your nearly naked body. There are situations where nudity is less acceptable than others, and I'd say that for example the Japan Festival here in Iceland falls clearly into the section where showing too much skin is out of place and ridiculous. Don't get me wrong, sexy cosplays are a positive thing, but there's a time and place for everything. If you're ever in any convention/festival asked to dress up more you've crossed a line, dress up immediately.
* Don't cosplay something awfully creepy/gory either if you're going to go to a convention or a festival where you know children will be present.
* Respect the other people's personal space as well. No matter how in character you like to be when in cosplay, don't go harass strangers.
* Photos are awesome right? Having someone want to take your photo is one of the best compliments there are. However, it's not a good idea to stop at a narrow corridor, blocking the way for others. Find a nice corner where you aren't in the people's way, most likely one is just a few steps away from you anyway.
* No indecent behaviour. Again, there's a time and place for everything, and a convention is NOT the place for dry-humping or sucking face in a public spot.
TL;DR cosplay does not give you or anyone else a permission to do something that's unacceptable in daily life. No means no, skimpy outfit does not mean consent, and by the way this goes for both girls and guys, no matter which one is in which role.