Hi can anyone tell me the difference between a skip tooth blade and a full tooth blade? When ordering for example you can either purchase a 5 or a 5f. I know what the full tooth blades are used for but whats the point of the skip tooth, thanks!! Also whats the difference between single sided and double sided thinning scissors. I know the obvious differences but what are the double sided thinners used for?? Thanks, you can tell im a total novice!!!