My girlfriend wants to cut her pubic hair what's the best way to do it with less irritation?

Hygienically!: Use lots of soap and water to clean, then use a guarded trimmer to cut the hair to avoid nicking or cuts. Then using a shave cream and safety razor shave with the direction of the hairs. One could use a depilatory and waxing is available. Staying dry and clean is important. After shaving use lotions and creams to avoid chaffing and irritation.