TweetUse gear that adds mass so that you don't lose muscle IMO.
The most common ratio is 5/40/55. That means you spend 5% of the time ramping up to max dose, 40% of the time at max dose and 55% of the time ramping down slowly. The ramp down is what is most important to slowly get your thyroid back to doing the work. For a first time, I personally would not go over 75 mcg but that's me. Some guys I know go up to 125 and some never go over 50, so it's up to the person.
As for length, no more than six weeks IMO. Some guys say no more than five weeks. Then, AT LEAST eight weeks off before going again.