I find he best time to collect shiners is in the spring. I use a dipnet from jonahsaquarium.com. There's a tiny little spillway near a bridge over white oak bayou here in Houston, TX, and also a park with ditches which lead to another nearby creek that I have found them in. I have found redfin shiners and what i believe to be weed shiners. They are quite plentiful in early march from a february spawn. The young ones I get take to aquarium life quite well and are eating by day 2. they also seem to appreciate a nice wavemaker for some flow near the surface.
I would love to hear the experiences of others in collecting different species of shiners.