I used to need another pair of hands to do any haircuts, but I have five long haired pigs now and am well used to doing them on my own. I use electric clippers - used to use scissors but I get on much better and much quicker with clippers.
I tend not to shear them all over, I bring their hair to just above floor level/around the pigs belly level, like a bob, the hair is still long but not trailing and tangling. I make sure I get the long bits around the legs and genitals. In summer I thin the hair out and this year did a more radical trim, but I found the thickest part of the hair is around the sides of the belly, just going towards the underside.