When you catch them, have a cooler full of ice with you. Fill your cooler full of ice and add enough water to fill the cooler about 3/4 way when you get to your spot, then add in a couple cups of salt and mix it around real well while trying to not freeze your arms off. Put your shiners directly into the cooler, pushing them down under the water. They will super cool and stiffen up a bit from the salt brine in about an hour or so. When you are ready to leave the location, drain the water and make sure the shiners are completely under the ice. When you get home, put them directly into freezer bags and and into your freezer. Do not add any water or salt to the bag. This is how we do shad and herring for catfishing, and they last 6-8 months in the freezer no problem. Don't let them thaw out completely when you go to use them, put them on your hook while they are still partially frozen and they will thaw within a couple minutes in the water. Doesn't work well with fatheads or emerald shiners, but works real well with golden shiners, creek cubs, common shiners, shad, mooneye, suckers, and of course panfish.