My tillering skills improved when I realized that most tillering needs to happen before bringing to a high brace.
As a beginner, I wanted to get 'er strung too soon, which for me, caused damage and avoidable set.
As others say above, floor tillering is one alternative, but I found it hard to know beforehand what constituted good floor tillering, as I was still learning. Long string at reduced weight, as George mentioned, is another alternative.
My goal on more recent bows, has been to almost finish the tillering before stringing, so taking the string on and off for the final adjustments is not much of a concern.