I have ALWAYS done it thusly: cut off top, cut root end and dig out that damned nasty butt, then peel, halve long-wise, slice each half long wise, then go back and cross cut into pieces as fine as I want them. As a home cook, this method has always served me well, unless I need onion rings for something special. I happen to HATE the butt end of an onion, which I always seem to get in my food, unless I yank it out beforehand. (When I say "butt" I'm referring to the thickened area at the root end of an onion.)