As a start, and if your arm is not tapered, the simplest way to get to "level" is to take a lined index card and place it behind the arm wand as it lays on the record surface. Line up the card's lines with either the top or bottom of the arm wand. That's a starting point, and no it's not precise - just by eye. But it is far better to have that reference point than trying to eyeball it without one. I couldn't believe how far off I was without it.
Enjoy,
Bob
Enjoy,
Bob