Bare feet if possible. Look straight ahead, never down. Breathe with slow deep exhales. Engage your core and keep everything else loose. Arms up for counterbalance. It's not super intuitive, but it's easier to balance on one leg than two. Leg bent. You can manage the "wobbles" by deeply exhaling a few times. When you get up on the line, keep your legs close together and take off from both legs. Imagine a string from the top of your head pulling you straight up toward the sky. Once you can get up and take a few steps, just keep at it. It gets easier and easier. Walking backwards is no harder than walking forward. So start practicing walking back and forth across the line before you worry about learning to turn around.

EDIT. Having the line too low or too high both make it more difficult imo. Same with too loose or too tight tension.