For leaf points, I sew right up to the tip. Sometimes I make an extra stitch, sometimes I don't. I fold under the seam allowance for the other side, then give my thread a little tug to pull the point out, then start stitching. It helps to pinch the fabric down a bit, to hold the point.
I also try to not clip my seam allowance too narrow for the point. I have a tendency to use a narrow seam allowance everywhere else when I needle turn, so I'll use a slightly narrower allowance for the first side of the point, and leave a quarter inch for side two. I really stuff it under when I turn, and sometimes use a toothpick to make sure it's completely turned.
For circles, I've tried lots of methods. I find that basting the circle first helps me. If I have a point I can ease it when I applique it down.
Janet