I cut my piggies nails roughly every two weeks but it depends on how much they grow.
I have a towel on my lap and put one of them on the towel.
If they wriggle I give them some food to keep them distracted and I hold one foot at a time and use nail clippers to take a small amount off each nail.
Acorn (one of my piggies) has both black and light brown nails.
With the black nails you can't see the quick (where the blood goes to and where you shouldn't cut).
So I am very careful with those nails and only take a small amount off. As said before you can use a torch to see the quick in black nails but I don't have enough hands when I am doing it on my own so I just air on the side of caution and take a really small amount off.
The light brown nails you can see the quick and so I cut above it so she doesn't bleed which would be uncomfortable for her.
It used to be a two person job where I would get someone to hold the pig while I cut the nails but I can manage with them on my lap on my own.
Hazel is normally amazing and will sit still for me without food but Acorn is more curious and wants to lick my hands and sniff the nail clippers which hinders the nail cutting quite a bit
I hope this helps