To create a straight hem every time I run a straight stitch along the whole end. This works great for curves also so don't be intimidated by those curves.
I then take it to my iron and press over right at the stitch line ¼ of an inch and then fold over and press another ¼ of an inch.
Stitch a straight stitch along the whole end. I match the edge of my pressure foot to the fabric for a perfect straight stitched seam.