A flip book works by tricking the eye into seeing motion though a sequence of shapes that pass rapidly in front of the viewer. The animation is done by drawing dozens if not hundreds of pictures so that each picture is slightly different than the last. For instance, to create an animation of a man walking would involve a series of pictures where a man's foot lifts slightly, is placed in front of him and then the back foot lifts and is placed in front of him.
Due to the incredible amount of effort involved in creating a flip book, lay ground work by plotting out the animation with stick figure drawings first. You lay these over the other flip them to make sure your animation looks the way you want it to. You will ideally be looking for a pace in your animation that is smooth but not overly slow. Add steps of animation in between sections that seem too jerky and to remove steps if you think the pace is too slow.
Creating your final animated flip book will require much more detailed illustrations. This means that you will have to draw the same parts of your characters over and over again. A good way to speed up this process and ensure the details remain the same do is to use a light box. A light box is simply a table with a hard semitransparent piece of plastic over a light. This allows the artist to trace easily with almost any type of paper. If you do not have access to a light box, you can use a window instead.
To make your animation as crisp as possible, ink your drawings. Bear in mind that each drawing needs to dry separately to prevent pages bleeding together or smearing.