I know there are some photographers out there who like how they edit something and once it's finished, that's it, no more alteration. But for me, there is always time to alter a photo.
I've always had this belief that I shouldn't be taking a photo for myself. I should be taking the photo for them, so they show off their costume to the world and if the photo I took isn't good enough, they won't upload it to their page.
One of my previous project, after I did my initial edit, we both wanted to make sure these photos was the best for the both of us. So I invited her to make as many critical points about the photos so I can make the changes. Out of the 40 I sent them, I was given 28 photos needed changing. This of course hurt my pride but I had to think, they were making sure that we both has amazing photos. Some of the pointers and subsequent edits I've made since, has made me improve on my post editing skill. I even learns about how to add contouring onto people.
Youtube and articles are a great resource to find tutorials on how to edit with photoshop. Also asking friends to be honest about a look of a photo really helps. I have a core set of friends whom I trust to give me pointers about any photo I send them.
I don't know if this apply to many other industries, but asking for improvement isn't an easy thing to ask for but once you do, an improvement in the end product will always be the result. Do if you are a cosplayer and there is a photo taken of you which looks good, but only a slight tinkering is needed, try and not be afraid to tell the photographer. Some might not appreciate it but some will certainly take the advice and do what they can to improve it.
One last point, FOR THE LOVE OF COSPLAY, DO NOT EDIT PHOTO YOURSELF. Editing without permission is something which will quickly blacklist you. Even if the edit is for the better, you would have broken the trust of the photographer and you'll be quickly blacklisted. These edits include but not limited by, smoothing, colour change, scene removal, letting someone else edit, removing of watermarks, instagram filter, moving picture filter, etc.
Let me know what you think about the subject I just talked about.