Is there anything in particular I should know about using a flat file on my edges? Do I need that other tool or can I just use the file on the ski base? It seems like I should go tail to tip and at a 45 degree angle, but what about the file itself, is there anything specific I should definitely not do with the file? Do the grooves on the file need to be in a certain direction? Just looking for a bit more detail is all, thanks!