You must understand the basic 2D design element:
movement, center of interest, value contrast, volume, size, perspective.... so on and on....
As for paneling.... there is no set way to do it, whether drawing the picture first, or draw the panel's first, or draw the panels and the pictures back and forth.... it's all upto the artist, as long as the result is satisfying to the artist. Just experiement and find the best way that suits you.
1. Panels must support your content: That's the most important thing.... if one line is going over an important character's head shot, omit that line and let the character stand out~ If one frame is more important than the other, you wish to make it a focus on the page, make that frame larger than the others, sometimes it can even overlap other panels alittle. However, being overly complicated