Trystan has written an excellent primer on copyright for costume bloggers that’s worth checking out. It’s a good rundown on the essentials and can help us all determine what’s legal to post and what’s not.
And while we’re on the topic… I want to boost the signal on one particular portion: crediting others for their work. I can’t tell you how many times I’ve seen people post about something online that they’ve made or “researched” and I just KNOW exactly whose work they’ve used — without crediting the person who originally came up with the technique/did the research. It sucks, because it can make the original maker/researcher feel like not sharing their techniques/research if others are going to essentially appropriate it — take the credit for all that hard work.
Nobody’s perfect, and sometimes we just plain forget, but if you try out somebody else’s technique, drop a mention! Even if you improved on it; you can say “I started with Jane Costumer’s tutorial, and found that if I did X differently it worked better for me!” If you draw on somebody else’s research, just add a mention — “Jane Costumer’s article on Obscure Hat from Obscure Town got me thinking…” One way I like to do this is to have a “Useful Links” section on my project pages — I can just list the sites that I found useful, and I know I’m covering my bases.
Costuming is a small world. When you DON’T give a shout out to others for their work, we are all thinking, “Wait, hasn’t X done a lot on this?” or “Gee, it sure sounds a lot like Y’s research/method.” And it looks tacky, even if you didn’t MEAN to take credit for their work, we are probably thinking that you did… so to avoid looking tacky, drop a quick mention and/or link and then you know you’ve covered your bases!