Dread,
I'm sure if someone hasn't already told you, you'll soon learn this from practice and reading, tension to me, is the cornerstone of lockpicking. From what i've gathered after sorting though endless USEFUL pages on this website, i've dwindled it down to this:
LIGHT TENSION = equal to the weight of your finger barely resting on the tension wrench, barely noticable plug spin movement
MODERATE TENSION = relaxed weight of your finger set on the tension wrench and slight but noticable plug movement
MODERATE MEDIUM TENSION = weight of your finger on the tension wrench equal to the amount of force necessary to close a safety pin and noticable plug movement
HEAVY TENSION = maximum pressure of your finger on the tension wrench causing it to flex more than 3-4 degrees and maximum plug movement while in the locked state
From what I've learned here on this site from reading, pulsing your tension, or trying different tension wrenches works well. The differences in the degrees of tension equal the type of feedback you receive from the pins when you SPP (Single Pin Pick). Example: I use Heavy Tension on an American 5200 Series lock, result, I can "feel" within my tools, fingers and the lock, when the pin meets the shearline because it results in a "crack" that can be heard and felt.
Pro - I can hear and feel this with each pin,
Con - I have to apply more upward pressure with my picking tool
Result - Personal preference gained by experience.
I struggle alot from varying tension with different locks, hopefully my posting is accurate and doesn't misguide you. But it's definately helped me and i've come a long way in a very short time because all I do for about 4-5 hours a day is read on this site. Eventually what you'll find is that everyone says the same things: Practice, Tension, Practice, Single Pin Pick, Practice.
Hope this helps.