When I but am using denim from jeans, I cut the seams off. Then I use a #16 needle. As I work along, the seams are ironed open to avoid huge lumps and bumps. When I include the pockets as part of the square, I cut it so I don't sew over a bug bump.
Use a strong machine, a good strong needle, don't sew over pins and go really slow. Be patient. change the needle every few hours. That is what works for me. Gwyn