Most mixed drinks call for ice cubes to be used, which are often available locally with a supplier. You can also make your own, however creating ice cubes that are as crystal-clear as those from a supplier can often be difficult. Some tips for a smoother cube:
Use softened water filtered by a reverse osmosis system.
Use warm water, which contains less dissolved gas.
Reduce the temperature of your freezer so that the ice forms slowly, reducing the problem of dissolved air bubbles.