So recently when I sew thick or slippery fabric, the needle and thread just won't go through smoothly. I always end up with horrendously sparse stitches which doesn't do anything for the costume.
Then my mom taught me this trick; rub candle wax along the seam lines.
According to my mom, the theory is that fabric like these have too much friction and the needle is unable to penetrate the fabric smoothly. Rubbing The fabric with wax makes the surface slippery and allows the needle to slip through.
I'm not quite sure if scientifically that's correct but it worked. Hopefully this tip is useful !