To make the opening of clams easier, put them in the freezer for about 10 minutes. This will relax them so that you can insert the clam knife more easily. Note that larger clams may take a little longer. If the juice has turned icy, just let them sit for a few minutes before serving.
When serving clams casino or clams or oysters on the half shell, present them on a platter of rock salt. This will not only look pretty, it will prevent them from slipping.
To ensure that your fresh clams are free of sand, try soaking them in fresh water, sprinkle some pepper flakes on top and wait an hour or two for them to spit out those pesky grains of sand.
Another option: try soaking them in fresh water and add a few sprinkles of cayenne pepper.