Keep a careful schedule.
One foundation of any program a trainer sets up for you is based on the idea that fitness gains come in response to stress: You stress the body, you rest while it adapts, and then you stress it again. But there's a fine line between just enough stress and too much, beyond which lies the clinical condition known as overtraining, characterized by declining strength. When it's time for the next step, use the so-called Texas Method that's used by many trainers, with a high-volume Monday, a light Wednesday, and a try for a new personal record (PR) every Friday. You can find other options in 'Power Training,' by Robert dos Remedios. You'll be tempted to do other exercises, too, but you'll see the most strength gains if you stick to the formula.