Most cocktail gadabouts drool when periodically getting behind the bar at favourite establishments. This is almost totally due to the large and bountiful supply of high quality ice. Denser and larger cubed ice melts slower when used for mixing, meaning the cocktail ends up less diluted. This is obviously a good thing. Unfortunately, I don’t know anyone who has bothered to invest in the high cost of a Kold-Draft or Hoskizaki unit in their home. Instead, I’ve taken to making high quality, dense ice by following steps available online (for example, http://gizmodo.com/5945245/how-to-make-the-perfect-ice-cube) to freeze water with as little air in it as possible. I purchased multiple Tovolo silicon molds in either the 1″ or 2″ sizes depending on what you’re doing. When ready, I partially vacuum seal them in Foodsaver bags to keep them from absorbing other flavours in the freezer and to keep the ice fresh. The vacuum will crush the cubes so it’s important not to let it get to that point. A cracked cube obviously defeats the purpose of all the work. It works well and I always have a good supply of quality ice. Ice makers in refrigerators produce the half-moon shaped cubes that melt quickly and overly dilute drinks when mixing. It’s not the absolute end of the world, but there’s no doubt they melt faster and therefore alter the composition. If using inferior ice, it’s recommended to fill the vessel with it and shake/stir for half the time (5 seconds).
As far as ice served in cocktails, never ever use the ice you mixed with and never use the half moon cubes described above. For this purpose I always keep various types of molded ice in sealed bags in the freezer, including 1″ cubes, 2″ cubes, cylinders for Collins glasses and spheres for Old Fashioned glasses.
Also, there are many cocktails that require crushed ice, especially in summer, and I usually crush the ice with a Waring professional ice crusher a bit of ahead of time and place the bin from the crusher in the freezer.
Lastly, as described elsewhere on this site, purchase a cheap copper aspic mold at a flea market or on eBay for punches as the ice melts slow enough to avoid overly diluting the punch. Line the mold with sliced citrus, then a layer of crushed ice (to keep the citrus from floating) and then fill with water and freeze in advance. One word of caution on this from experience, make sure the mold fits in your punch bowl before purchasing!