I am using dyntopo, and when I try to shape a square down into another shape that I want (torso, arm, etc.) it pushes some vertices too far down. Can I adjust that somehow?
You can press Shift+F to adjust the strength of the brush you are currently using.
You can also adjust the detail size with Shift+D (This will display as a percentage or as a pixel count depending on the detail type being used.) The manual has an explanation of each one.
Changing the radius of the brush with F as needed is also useful.