Don't forget to play with tempo, static holds and muscle time under tension when you're lifting.
It's boring and shortchanging to just lift up for 1 second and down for 1, mindlessly. But it's something I regularly see -- people throwing their weights around too fast. Lift and lower too fast and your merely cheating on yourself with momentum and gravity.
As a basic rule of thumb many experts suggest 2 second on the positive contraction (when the muscle is shortening), a one second static hold at the top on the movement and 3 second on the negative contraction (when the muscle lengthening).
You could try going super slow on each contraction. Try doing a bicep curl that takes 4 to 6 seconds to curl up and the same time to lower.
Or you could do one set where you take 1 second to raise and 4 to lower, and on the next set do the opposite -- 4 seconds to raise and 1 to lower.
And don't forget static holds to really smash your muscles. In a bicep curl maintain a static hold at 90 degrees. Or hold a squat half way down.
It's gonna hurt. But in an oh-so-good way.