Thumbnailing is used to generate a range of ideas or designs. It is useful for communicating an idea or project goal without becoming burdened with detail. Should be clear, easy to process, and simplified. When thumbnailing & storyboarding, there are several things to consider being effective.
C.A.S.E study
Camera and sets: Consider who is in the frame and how should they appear. Use character model sheets and reference material with your thumbnails to help convey the right character and action. Have an awareness of the camera shot type and overall composition – know what the last thing should look like when sketching out your scene.
Action: Aim to simplify any action within your storyboard. E.g.: if a character is gesturing with their arms, can you contain all the poses in one storyboard frame rather than several, or expand the size of the frame to denote the character appearing in the scene. Make sure you record any secondary action and the camera movements and show any dialogue or sound effects.
Space: When producing thumbnails, be mindful of how you represent space and position. Where possible, use a floor or wall grid to help establish a perspective in the scene. You could also add a centerline to your character to help show depth and again perspective of your character. Last, mise en scene. Populate your space to establish the location and help ground your character to scale.
Economy: During the pre-production stage, we must consider the potential costs of our shots. In animation, producers are strategic about how many assets will need to be produced and individual elements animated for a show. E.g.: Sets often follow the shoebox method, with three angles available from just one set drawing. This means artists will only have to draw one larger set design, instead of separate drawings for each potential shot type.
I will look at a storyboard and analyze it using the C.A.S.E study. I will look at this storyboard from WALL-E:

The storyboard is of the lighter scene from WALL-E. It shows WALL-E and EVE and EVE is holding a lighter.
I made some thumbnails for my project, illustrating some scenes

