Dry/dropper is how I usually start out. If the water is big, I'll use a #6 or #8 hopper and #16 bead head nymph. Now, water is low and clear, and I'll "prospect" with a #16 Foam body caddis, dragging a #20 or #22 nymph of some sort. When water is really clear and/or fish are very "educated" you may need to go to #24 or #26, on your nymph, and use a finer tippet. The thing is, you'll need to try different flies and sizes, to see what's working. In addition to learning to read the water, learn to read rise forms, and adjust flies and depths accordingly. If you see fish "porpoising", they are probably chasing bugs stuck in the film. If all you see is a tail, they are probably chasing emergers, a little deeper in the column. If they are eating adult bugs, on the water, all you will see is a slight bump in the water, as they sip. Keeping in mind, that most of the time, they don't feed on the surface, but they do feed, most of the time.
As for casting practice, I still go out (after 35 years of fly-casting)to the green space, and try to hit dandelions, with the little tuft of yarn tied to my tippet. Stand under a tree, and practice side arm. Try to roll cast. Cast into the wind, with the wind, across the wind, on both sides. Point being, it's a lot easier to learn casting, away from the confines of the river.
Good luck and have fun!
