Gary Borger, in his classic book "Nymphing" describes a technique called "The Strip / Tease" (we just called this 'working the nymph' when I was a kid). The method is pretty simple: cast your nymph across - up or down & across, wherever - so that it gets to the bottom in the part of the stream where you think the trout are laying. The, very slowly, strip in short amounts of line (using the hand twist retrieve). Start & stop the retrieve often, allowing some time for your nymph to drift down stream. This will mimic the natural nymph movement well - if you're on the bottom.
You can also use this tactic casting straight down stream, if you're in lower water. It makes your fly look like a nymph struggling in vain to move upstream.
This strip / tease method is very effective in the early season, when there's more water in the stream & the water temperature is colder. Also, use this method anytime & anywhere you see the trout flashing their sides. When you see trout flashing their sides, it most likely means they are rooting the bottom, trying to dislodge some nymphs from the bottom.
One thing about this technique - most anglers do it TOO FAST. You must go very, very slowly!! As a general rule of thumb, the colder the water the slower you must retrieve. Give your fly plenty of time to sink.
As you retrieve the line with the hand-twist method, keep the line under your index finger of your rod hand. You need to be in constant contact with your fly to feel every bump & titch of the line so you don't miss any strikes.
Finally, if you're using any weight or split-shot to get your fly down to the bottom, you need to think about where you put your weight on the leader. In order to mimic the real nymphs, you need to know how far off the bottom they're coming when they lose their footing. There's no way to know for sure, so you must experiment with how far up or down on your leader you put the weight. Keep moving your weight up or down your leader until you start picking up strikes. If you move to another spot on the stream, you might have to move the weight again, but at least you'll have a reference to start from.
So, to summarize:
1.) Cast your fly so it gets to the bottom where the trout are. Give it lots of time to sink.
2.) Slowly retrieve your line in a start & stop manner.
3.) Experiment with where you place your weight (if any) on your leader.
4.) Keep in constant contact with your fly & line so you can feel the fly.
5.) Remember to go slow. Most anglers fish this method too fast.