It's simple, yet I spent an entire trout season, aged 14, trying to catch trout as my angling mentor did. I caught 13 trout the entire season, which caused me great distress. He caught some 260 trout that spring, not that we always fished together. And that was a relatively low figure compared to successive accomplishments.
The next season, I caught on. I caught over a hundred trout, my fishing log from 1976 stacked away somewhere. (But the log I use today is consistently the same format I used from 1975 forward.)
Here's what you do:
1. Use the lightest, shortest (not under 3 1/2 feet) super-ultralight you can purchase or make. Mine is so light it's a wand. I can bend the tip back against the rod.
2. Smallest spinning reel possible.
3. No more than two-pound test low diameter.
4. Typically use no more than the smallest snap available for weight and attach either one or two 2-pound test leaders to it with size 14 hooks. (I've caught double headers, but can cast a single salmon egg more than halfway across the North Branch Raritan River.)
5. Feel the current. That's the thing you really have to learn. Eventually, it's second nature to control drift. But perfect drifts don't always prove possible; you have to settle for the best monofilament or flourocarbon can perform with such variables as wind and stream current.
6. Life is not art; art is applied to life. This means that imperfection will happen, but persistent application overcomes slight disorder, which shouldn't be resented, but allowed. If current doesn't seem to run through your own body, so that you feel it subtly, and are in touch with it, you're not in the natural flow of experience you want to achieve and control.
That's basically it. Take along some tiny split shots (tin) for deep, strong currents. Forget salmon eggs for brown trout, although we have caught some this way, back when browns and rainbows got stocked together.