I teach needle turn and it's my favorite. Here are some tips.
Check to see if your thread is too loose (slip the needle under a stitch and pull up, if the thread forms a loop, pull the thread tighter). It's easy to tell too tight--it puckers.
Take small stitches (somewhere between 1/4 and 1/8 inch, depending on how tight a curve is being sewn.)
Clip for inner curves and for outer curves take a "V" shape out of it or cut the seam allowance down to 1/8 inch.
Rather than pinning the patch in place (it moves even when pinned), try several tiny dots of Roxanne's Glue Baste It. That's all I use now. It's water soluble and washes out.
If there is a point you just cannot get to behave, take a stitch into its point. Pull the thread firmly and the point should disappear.
Stick to it. Needle turn does take time to learn, but is extremely rewarding and the results are wonderful.
SandyQuilter