GeeWhiz! I wish you were closer....I am doing a machine applique' class for our guild and guests ( for FREE) on January 19th. These ladies have given you some very good suggestions tho! All I can tell you is the same old, same old...PRACTICE, PRACTICE, PRACTICE. I instruct all my students to take a 10" or 12" square of fabric, use your chalk pencil and draw a square, circle, oval, figure 8, diamond, triangle and whatever other shapes you can think of. Back your square with a stabilizer or a medium tear away product. Also have a piece of scrap with you stabilizer under it and figure out your stitch you want to use....a straight stitch, a blanket stitch, a zig-zag , a satin ,or a decorative stitch, etc. Figure out your stitch length and width....be sure you are using the correct foot/ open toe, usually...and have a clean machine, a sharp needle, and the correct thread.....
For an outside corner ( squares, triangles, etc.)...stop your needle in the down position at the outside of the "point" of the corner, turn the fabric to where you will start the "new" line of stitching to the next corner.
With circles and ovals and curves, don't get over anxious...stitch as slowly as you are comfortable and occasionally stop your machine in the needle down position, on the outside of the shape, as often as needed and gently turn fabric and stitch a few more stitches and then repeat as needed....with triangles and stars and very sharp corners....this gets tricky....stitch to the point, needle down on outside of point, turn fabric to a 45 degree and make one-two stitches (depends on what your stitches are...this is mainly for satin stitches... and then then needle down and turn again to your line of stitching.
As said previously...practice...it will suddenly click and then you'll have it. Even after all these many years that I have been doing this, I still have my practice squares to figure out my stitch and the sizes and to figure out a corner, depending on the stitch I use.
Good luck with this and if I can can be of other assistance, please PM me....and that goes for all others who might need a little help.
Hugs and Happy New Year