As far as flies go, you have to get info on a particular stream you are fishing. See what insect life is prevalent. If I fish a fertile stream as Spring Creek or other limestone streams, I’ll use natural imitations. Learning when the different species of mayflies and other aquatic insects hatch helps cutting down on guessing. I nymph / wet fly 90% or more of the time. I usually don’t go to dry flys until I see fish actively rising. I’ve been doing this long enough that I recognize hatches. If you fish stocked streams that don’t have a lot of insect activity, as we do in SW PA, go with green weenies, mop flies, San Juan worms, honey bugs, sucker spawn etc. Wooly Buggers are a good streamer to start with. I use a lot of Euro flies with a normal trout set up usually with a strike indicator. I’ve just been doing it that way for so long that I have become very adept at it. I do usually fish 2 to 3 flies at a time. I’ve caught lots of trout, even steelhead, on a Red Dart. Sometimes you have to show them something different even if it’s a junk fly. I also say the smaller the stream, the smaller the fly. Same with slow water. As far as weight goes, if you aren’t getting snags, you aren’t getting down deep enough. I tie my own flies so I don’t mind risking a snag. If you’re snagging all the time, reduce the weight.