They help you see what type of bonds form in molecules by just focusing on the outer electrons. You can "see" how each atom can share electrons to reach their magic number of 8 electrons in their outer orbit. Atoms dream of having 8 atoms in their outer orbit.
You can use a drawing or use small beads or objects to represent electrons and work out the electron arrangement. Use a different color or shape to represent the electrons of each atom. Move them around until all the atoms have 8 in their outer orbits. (except Helium and hydrogen-they want 2 electrons)