Frame by Frame Animation

Frame by frame animation dictates that you re-draw all elements of the previous frame, making only slight changes. Over multiple frames, the changes build up to an illusion of motion.
 
Although still laborious, Flash makes this process significantly less costly in terms of time. Instead of redrawing all elements of the previous frame, we can duplicate the contents of a layer by simply inserting a Keyframe on that layer, and then modifying the contents of the new Keyframe.
 
Any background or static elements that do not change should be placed in their own layers. As long as those layers extend to the number of frames of the rest of the animation, no other changes need to be made to those layers.

For each frame of the (stick figure) animation, insert a Keyframe and change the graphic slightly:

Insert a Keyframe

Select the next empty frame
 
(The first time through, only frame 1 of layer 1 contains anything, and the layer ends at frame 1. Selecting the "next empty frame" in this case would mean single-clicking on frame 2 of layer 1)
 

Insert -> Keyframe
 
Inserting a Keyframe copies the entire contents of that layer into the new Keyframe, where they can be modified without changing the contents of the layer before the new Keyframe
 

Drag an end of a line:

Scale/stretch a line or line segments

Select the line
 
To select multiple objects, first select the first object, then Shift-select any additional objects
 

Select the Scale tool
 

Drag one of the handles to scale (corner handles) or stretch (middle handles)

Rotate/skew a line or line segments

Select the line

Select the Rotate (same as the scale tool) tool
 

Drag one of the handles to rotate (corner handles) or skew (middle handles)




Add a corner point to a line:

Hold the Alt key down, and with the Arrow tool drag on a line (or a curve) at the point at which you want to create a corner point




Redraw (a piece of) the original graphic:

Select and delete (a piece of) the original graphic
  (Example: left/back leg)
 

Turn the Onion Skin feature on (to see the contents of the previous frame)
 


Referring to the (onion skinned) graphic from the previous frame(s), redraw the deleted portion, slightly changed

Turn the Onion Skin feature off

Repeat the above steps for each frame of the animation
 

Insert a Keyframe

Slightly modify the graphic in the new Keyframe (using a combination of the above techniques - drag, scale, rotate, redraw - or any others that are appropriate) until you have a sequence of images that, when viewed one after the other, gives the illusion of the stick figure walking
 

Open this example to see how each keyframe was modified slightly to give the illusion of movement.