Start by planning your story. Decide what you want to show in each frame. Then, sketch out rough outlines for the characters and the background. Pay attention to the composition and make sure it flows well from one frame to the next.
To draw a 4-frame comic, you need to think of a short and interesting plot. Sketch the main elements in each frame, keeping proportions in mind. Add details and shading for a better look. Make sure the frames connect smoothly.