What's the best way to keep crickets alive and healthy for an extended period of time?  Any suggestions?

I just add a few pieces of raw potato or a couple of orange slices to the cage and keep them in a cool,but not cold area out of the sun. I have kept them alive for days and days doing this.

I used to keep mine in a 10 gallon fish tank with screen lid. They like an empty egg carton to hide in.

Thanks.  I just want to have some crickets in advance of a trip and don't want to stop and get them (there are very few bait shops in this area).  I believe the local Pet Smart has them but they won't open until after I've been on the lake several hours.

PetsMart has something called flukers cricket quencher, it looks like chopped lemon jello, I use it in place of water to keep my crickets from drowning. We have a gecko so I always have crickets around, one jar lasts me 6 months or more. Other pet stores probably have it too.

potato and definitely get  a piece of egg carton in there