Do not have the jeans on! Have them on a table. I used a serrated steak knife in a left to right motion with a good amount of force until there were tears in the jeans. Continue this
Pull at any pieces of fabric left in the sets of strings where the holes are.
You can also use your hands to rip the holes bigger
I used these jeans as practice for the pair of Converse I studded afterward. Push the stud through with your hands and fold over the metal in the back with pliers.