Sake can be served both cold or hot,, however, you can also drink it at room temperature. Sake changes its taste depending on the temperature, so it is recommended for you to try various ways. Indeed the same sake can taste very differently depending upon at which temperature it is served. Generally the Japanese do not pour sake into their own cup (ochokko) but will fill their guests’ or friends’ cup first(the same thing with beer too actually). Once someone has filled your cup, take the bottle (tokkuri) out of their hand (or take another bottle if you ordered two) and fill their cup in return.