I struggle with the pointy points too, but a couple
of things that help are:
Sew down to the point on one side, then tuck
the other side under to make the point.
Use a toothpick to help tuck under stubborn seam allowances. ( I wear a ring on my left thumb when I applique and keep a toothpick tucked into it)
When you get the allowance tucked to your satisfaction
Take 1 small stitch right in the point and stitch it
straight down.
Maybe these tips will help a little. I am learning that the best tip is to practice, practice, practice. Mine are getting better the more of them I do.