In order to start your animation, you need to design your character. Remember that your design needs to be simple so that you can easily re-draw it multiple times.
You also need to draw your character from 3 different viewpoints: Front, Side, and Back. This way you will have a good reference for how your character will look for most of the shots you may do for your animation.
Below are some examples of some character design sketches. Note that some of them have facial studies on them as well – you do not have to do that. Some of them also draw the torso from the side without the arm so that you can see detail in the rib-cage area. This is also not necessary, although if you do it, I certainly won’t deduct points, as long as we can see how the arm will look in other views.