First time cutting nails

I rescued a guinea pig and I’m trying to find him a family. I know he needs more than I can provide, so I’m trying hard to find a good forever home for him.

I don’t think anyone has ever cut his nails. And I have never cut a guinea pigs nails. He’s very skittish, he’ll eat out of my hand and recently let me start scratching his chin, but he does not like to be held.

Could I please have some suggestions?