Fish are smart and while they're certainly not enduring a long and drawn out debate (as to how legitimate or illegitimate your fly is), they're going to be picky. Meaning, you're going to need a wide variety of flies and case in point—Umpqua's Ultimate Fly Selection with UPG Fly Boxes ensure you will have no shortage of options with tried and true flies hand selected for you. PS... they are currently all on sale.
Shop all options here: https://aventuron.com/collections/upg-fly-selection-boxes