It's kinda hard to give a single explanation of how to nymph. Water depth, current speed and direction, fish species, your skill all come into play.
I'd agree that not using an indicator would be ideal, but a lot of folks (like ness) can't see the dang line in most conditions. So, I like to stack the odds in my favor with an indicator.
Typically, you want to get the fly down quickly to the bottom but have enough buoyancy in the indicator that it just floats in the surface. That means you need the balance between fly, weight and indicator to be just right. Since stream depth and current can change within a few feet, it's nice to have indicators that are easy to adjust up and down.
Cast the rig well above the suspected lie for the fish, and mend upstream to slow the sunken fly to the speed of the water at the bottom (which is traveling slower due to friction with the stream bed). The fly should settle into the right spot and bump along. If it sinks down directly on a line with the current, it's probably a snag -- but give a gentle hook set anyway. You'll get a feel for how it's riding, and let the snags go after a while. Anything else (sideways, slight sink, whatever), set the hook. Move the drift up, down and side to side to cover the area, then move on.