Every animation job entails a lot of planning beforehand. If you're about to make an animated short, have a story in place no matter how basic it is. Work on the design of your characters and lock them down to the last detail before you draw a single frame. If you want to incorporate dialogue and/or sound effects, the planning process becomes even more critical. Remember to always record dialogue before drawing the animation.
When you're employing 2D, hand-drawn animation, having the right tools is vital. Hand-drawn animation requires the animator to see five or more layers of paper at the same time; thus, some level of translucency in the paper is required. You need to also hold the paper in place, so three-peg bars are recommended. Another valuable tool is a light box, which shines a backlight over your drawings. When buying a light box, try to acquire one that is able to change the angle of the drawing surface. You can also build one up at home if you want to save money.
There are two ways to animate a 2D animation sequence, according to the book "Character Animation: 2D Skills for Better 3D." One is "key-to-key" animation, which refers to key drawings that sum up the essence of the action. Once all the key positions are down, the sections in between are added. In the second technique, called "straight ahead," images are drawn directly one after the other. Straight ahead animation usually results in more vibrancy and energy, but distortions and size changes are more likely. Additionally, key-to-key animation lets you control the timing of the animation, like for instance allowing for slower movements by drawing more in-between images.
A thorough knowledge of how things work and move in the real world is perhaps the best foundation for successful 2D animation. When dealing with inanimate objects, play close attention to its weight, the force being applied to it and the way it interacts with other objects. When animating characters, especially those with humanoid characteristics, it pays to learn as much as you can about anatomy and how the different parts of the body are related to one another. Remember that even the simplest of characters must move, behave and interact in a believable, organic way.