Nymphs and Streamers, usually size 8 down to size 12.
For Nymphs I tie a Pheasant Tail bead head with some color dubbed in at the thorax: chartreuse, orange, or pink. Some of the lakes I fish have a large population of Damsel flies and I’ve seen the ‘gills get selective about that, just like trout do. I tie Damsel fly nymphs in olive and grey. Marabou for the body and tail, a couple of turns of peacock herl at the thorax, and mono-bead eyes (melt the ends of a piece of mono to form two buggy looking eyes).
For streamers as others have mentioned you have to have some Woolly Buggers. Black, olive, brown, and white. I also like the old classic Black-nosed Dace as well as the smallest Muddler Minnows I can tie.
If I was restricted to one species using one technique, I’d spend the rest of my days fishing for Bluegills with a flyrod. I love it.
Good luck this Spring!
Rootski