Not directed to anyone in particular, I just notice a lot of posts (here and on other forums, as well) from people seeking animators that tend to be very vague. Sometimes, people will be nice enough to suggest what else should be added, but in most cases, animators will just close the tab if a post doesn't appropriately inform them of what's necessary for a project. I know a lot of people are sincere in wanting to complete their projects, but a basic amount of communication is vital to accomplish that goal, so here's just a small little checklist of things you can include in your post! (And, of course, other people can add on to this.)
1) Type of animation/duration
Short, trailer, music video, webseries, game, etc., plus wether it's 2D or 3D. It's also important to give the animators an estimate of the duration of the product and duration of the project to the best of your abilities.
2) Genre or the premise of the story
Comedy, drama, horror, FPS, platformer, etc. I understand people can have difficulty posting their ideas extensively, but some people aren't comfortable working with certain genres or are more attracted to others, so the more information you can give at this point, the better.
3) Payment system
Up front, in royalty, an adaptation to whatever the artist usually works with, etc. If there isn't payment, specify that! But do know you can only expect so much in terms of quality without paying. Animation is a long term commitment that requires a lot of studying beforehand, so it's hard to ask for their time and their work without compensating them for it in some way.
4) Some form of visual development
This can be everything from a moodboard on Pinterest to actual concept art and work done so far. Even if you specify that you want a 2D short, for example, that can take many forms in terms of style, so it's important for animators to know what you're going for. I'd go for 5 example images for each style I want to specify (character style, BG style, coloring style, etc.). This is also where you could inform where your project is at in terms of writing, storyboarding and animating.
5) Roles necessary
Do you need a 2D animator, a 3D modeler, BG artists, 3D riggers, concept artists? They're all very different skillsets, and animators don't cover all of them (and if they say they do, trust me, they don't haha).
6) Where this would be posted
Under what name, as well. Would this be posted just on NewGrounds? Would you be the one posting it or the animator? Or would this be posted through a promotional YouTube channel for a book with credits given in the description? Or on someone's personal blog with credits at the end of the video? No animator wants to find out their work has been posted somewhere they didn't want it to be.
7) Contact information
While this seems to be the only thing no one misses, it's good for people to know where they can reach out to you other than the forum account they posted with. Lots of people prefer keeping work strictly to email communication, for example.
8) Good etiquette
This usually includes not posting multiple topics, using correct grammar and capitalization, and just being polite. You don't have to be fake, but something as simple as saying "if you're interested, please contact me here with your rates" instead of "tell me your rates" doesn't take much time or effort to do.
Example: My name is So-and-so and I'm the writer of the fantasy book, Awesome Book Name. I'm seeking animators to create a one minute trailer, give or take, within a period of six months to a year. This would be an animated trailer for my book to be posted on YouTube, giving credit and linking back to all artists involved in the description and end of the video. You can see a blurb of the book here (provide link or paste). So far, we have sketches of the characters here (provide link or include in post), but we would need people to storyboard this and animate it in 2D. We will also need background artists for this project. If you're interested, please contact authorname@emailplace.com with your rates and what role(s) you can take on. Thanks for you consideration in advance and I hope to be speaking to some of you soon!
I know this can all seem very obvious, but I do feel it's something that's lacking in a lot of posts, so I hope it can help someone out there. NG is a place to encourage this kind of creation, after all, and it can be difficult to do everything on your own. So good luck with your projects, guys!