I can few them between the trachea and the front neck muscles (sterno-mastoids). I like to take a pen and draw over my skin to know where to cut, despite the fact i never made the cutting. I advise you to do the same, because hitting your muscles making this cut is easy.
Its also good to use a knife you can stab, if you can. Dunno if the shavette i have can go deep enough, maybe i'll have a big traumatizing experience trying to make it reach there.