The best way to clear snow from a sidewalk is to begin shoveling while it's still snowing. This way the snow is easier to clear since it hasn't had time to become ice through freeze and melt cycles.
After the snow is removed completely, apply sand or a salt-like substance to the pavement to provide traction. Do not use table salt because it is toxic to the soil and kills plants and trees. Also, do not use actual sand, since it makes the ice more slippery. Calcium chloride and potassium chloride are more environmentally friendly, with calcium being the top choice.