Using reference is one thing. Copying directly is not cool I only see this as lazy. Unless of course this is what the commission or piece is like fan art (which I love). But still be mindful the Internet is a small place among artist. Especially the animation community.
How to use reference then? I take photos and share them on twitter, instagram, tumblr and facebook. Here are some I have gathered this year. It is helping show how my mind works and has a large library of categorised sky textures and backgrounds . That I can now digitally capture as well and group into my favourites .Just double click to check out the larger image. Feel free to use my reference too. I love to share my work.