i won't wax or shave ALL of it so I tend tp us e arazor a tidy up. The answer is indeed carefully. However I find it easiest in the bath lying on your back with your knees in the air and I usually use a chepo conditioner as shaving foam.
You need a sharp razor and a steady hand!
Even easier if you get someone else to do it for you! But you have to trust them and they have to understand what's at stake if they lose their concentration.