What is the proper way to serve and store Saki?

High end sakes should be served chilled, not at room temperature. The best way to serve is straight from the bottle into a sake glass (or a large short glass). Put the glass into a bowl or other vessel and overpour the sake just a bit. This is very traditional (the Japanese usually use a small wood box) as it denotes overflowing of friendship. If it's really a nice bottle, then do not mix. Only low grade sakes should be mixed. If you must, you can substitute sake in just about any vodka drink.

Store it in the fridge. When you plan to drink it, let it warm up to room temperature and pour it into a small glass. Sipping it is best. It is also best to finish it the day you open it, though it can remain drinkable for weeks after opening if kept in the fridge. If it's not good sake, you generally heat it up before consuming it to mellow the flavor. Sake bombs are also a fun way to drink sake. You get a dry Japanese beer, pour a shot, pour the beer into a glass, drop the shot and chug.