I do mark registration marks for open areas, but go ahead and draw out as much as you need to--it's only chalk (or water soluble marker). have you done any pantos? A few may help give you more confidence on moving the machine.
draw, draw,draw when you are watching tv, during meetings at work!, anywhere--it builds muscle memory. Use some stencils to help you have some lines to follow--but realize that those are not set in stone and just give you guidance on most FMQ. Relax--if your grip is too tight it shows on the quilting--one friend has a glass of wine before starting--but that may not work well if you are on rented machine! so do some deep breathing and shoulder rolling if you find you are too tense. And you are right, practice, practice, practice--it gets better!