These are the simple rules that you should follow when creating artwork for video:
- The color should be set to RGB, and the frame size (Atrboard of Image File dimensions) should be the same dimensions in pixels or points as the video frame size.
- The exception to the frame size rule only applies to raster (pixels) images and it is that the image you create should be as large as it is going to be when it is in the hero position in the video frame so you never have to scale the layer more than 100%
- Every element that you want to animate needs to be on a separate layer.
- When using Illustrator you should have Snap To Pixel and Pixel Preview turned on in Illustrator's View menu
- All thin horizontal and vertical lines should be at least 2 pixels wide (points) and perfectly aligned with the pixel grid
- No artwork should extend beyond the Artboard.
- Any Illustrator layer that you want to convert to a Shape layer in After Effects must be filled with a solid color and have no brushes or effects applied to any path
- If you want to reveal a Path using Trim Paths in After Effects, you need to duplicate the layer with the path that has the brush stroke applied, remove the Brush from the top copy, name that layer Track Matte, and only convert that Vector Layer to a Shape Layer.
- Set all raster effects applied to layers in Illustrator to at least 150 PPI so you can scale. up the vector layers without the layer effects becoming pixelated.
- Do not let any object on any layer extend beyond the boundary of the Artboard. If you use video templates there is a second large artboard directly behind the template artboard (Check the Artboards Panel). This larger Artboard will prevent layers that extend beyond the video video frame-sized artboard from being cropped.
Follow those suggestions, make sure that you manage your colors, make all PSD files at least 16 bit color, and you should be fine.