I used to work in a pet store and was in charge of keeping a great deal of expensive fish alive, and while a live well is defintly not an aquarium what I learned dealing with the fish in stores has helped me a great deal keeping fish alive in a live well.

First I try as often as possible to keep fresh water running threough the live well, this is much easier to do in a boat with a pump that can constantly pump new water through the live well. Old water tends to be warm and dirty. Hot and dirty water kills fish faster than anything else.

In small live wells that most guys in kick boats use it is most likely harder to keep fresh water in the well but if you focus on keeping the water cool you will loose less fish. You can circulate the water all you want but if the water gets too hot your fish will die. A frozen water bottle or two can be put in to the live well to keep the temp down.

Fish drugs (Bass Alive, ect.) help to keep fish alive by doing a couple of things first they keep them calm, and the less stressed out the fish are the better chance they have at surviving. Most fish drugs help the fish to more eisliy process the O2 in the water, making it eiser to breath. And most fush drugs help to protect the fish's slime coat as well. I use fish drugs when I can not be pumping new water through the well (for example in a boat when running or when in shallow weedy water when clogging the pump might be possible)Just remember all the drugs in the world wont keep your fish alive if the water gets hot or you do not keep the water airiated.

Lotta ins, lotta outs, lotta what have-yous