Nothing wrong with Woolies!
I'd suggest you get a good tying book -- one that covers the basic styles: dries, nymphs, streamers, wet flies, poppers. I assume you've got a vice, some tools, threads, hooks, etc. Then get the materials you need to tie the ones you're most likely to use. On my list would probably be Stimulator, Madame X, Elk Hair Caddis, Adams dries; Pheasant Tail, Hare's Ear, Copper John, Prince nymphs; Clouser Minnows, Wooly Buggers, Thunder Creek streamers; I don't fish wets much, but I'v always got a few soft hackles with me. Poppers are fun to 'tie' from styrofoam or cork bodies. Check the suggestions for materials you'd need, but I'd say get some buck tail, elk hair, marabou, gold wire, hare's mask, pheasant tails, at a minimum.