I recommend to keep practicing. The biggest hurdle is getting the machine speed/hand coordination part down...and practice is the only way you will do that.
I took one class a few years ago...then I just practiced. It was a while before I was willing to take the chance on a "real" quilt...but I finally did. The more I do, the better I get. I practice a little before EVERY quilt. Early on, I did not do well with stippling, but did ok with loops and swirls. So once I mastered those, I practiced stippling more. I am much better at that now, but I still don't care to do stippling. I like the look, but find it boring to do on large areas. Also, when I first started, I used thread that matched the back and blended in more on the front so my mistakes weren't so noticeable. Now I am not afraid of contrasting thread.
Loops and swirls are more forgiving than straight lines or large designs that you might not be able to do smoothly without repositioning your hands. Is there a design that you think you do well? If so, try to master that one then try others. Another thing is to take a fabric with a large print and practice going around the designs.
My favorite foot is a spring FMQ foot. I love the Machinger's gloves best...I never quilt without them. I also like the supreme slider, but an inexpensive substitute can work also. I didn't think the bobbin washers made a difference in my machine (my bobbins are contoured, so they don't make full contact with the washer). I prefer not to mark on a quilt, so mostly I either totally freehand it, or use golden threads paper or sulky solvy if I want a more consistent pattern. When I am following a drawn pattern, I am rarely right on the line...but once the lines are gone, who will know? Be sure the weight of your quilt is supported, the drag will affect your stitching too.
Good luck!