How do you keep store bought shinners alive.

If I have shiners that see the light of day long enough to even think about dying in my minnow bucket, I just try to keep the water really cool.  I may take some ice from my drink cooler and drop it in my bucket.  During the winter (I'm in the south) i usually don't have to worry about losing any.

If you carry them in a bucket, I don't know...I guess you need to fish fast!  But if this is a more general question, I fish minnows year around and I have a couple of tricks to share.  First of all you need a high quality aerator, preferably round (if it's rectangular those stupid little fish get caught in a corner and drown).  I have a built in that pumps fresh water from the lake/ river constantly.  When we are running I turn on the recirculator.  Another summer trick is to put a small amount of commercial ice in the live well peiodically.  There is another system I have read about but don't have. This set up pumps bottled oxygen into the water. The theory appeals to me but my current system works pretty well by itself.