When I was studying illustration, the director of the school used to say: "We are big on the shoulders of giants"
If you are lucky to work in a studio, you'll be able to check the storyboards, animatics, recordings of actors , the work of the art department and the preproduction of the animation department (Tests, video references, characters bibles,…) which will help enough to create your shot.
But however extensive ia all this material, you will only have a starting point…
Your best ally to document yourself and increase the quality of your actings will obviously be internet, as it puts at your disposal a database of almost infinite…From another hand, if you do not know how or what to look for, it will be easy to get distracted and lose the day (like ending watching videos of kittens, for example…)
That's why, I leave you here my methodology when looking for reference and avoid getting lost along the way:
The first step, will be to search on youtube some movie sequences where actor or character look like to the one of your shot. This will allow you to get into the character and direct your acting.
Nothing better than a good own video reference to understand the body dynamics. But sometimes we face that we can not perform the movements. That's why it's good to have a look at those different databases to understand the movement, the biomechanics, the weight and balance:
• Reference! Reference!
• Endless Reference’s channel
• Rhino House
• Global Zoo
• Popular Actions channel
The next step is to search some pictures to find attitudes poses, that is to say, some poses that represent with the whole body what a character thinks or feels. There I look at the lines of action, hands poses and facials.
• Google : Pose
• Pinterest : Types of poses
Personally, I use animated Gifs a lot to document myself for the actings. This format is widely used today to illustrate conversations in chats or forums and they usually synthesize specific messages. I usually associate the word gif in the google search engine with a type of emotion or expression to find gestures and timing information.
• Emotion & Reaction GIFs
• Reaction GIFs – Say it with a GIF!
• Getty Images
At last, to motivate me and get inspired by the work of great artists, I have a look at some drawings and animation libraries to bring exaggeration and appeal to my actings.
• Frame by frame
• Living Lines Library
• Too many disney gifs
• Disney Screencaps
Once you have all this material, you can do a quick edit with Quicktime to keep only the material you need. ( Use Rotate, Flip, etc…)
I hope that was usefull…