Rince rice thoroughly (this is a given, we all should do this), then put in a pan filled with approx the same depth again of water (ie, if the rice is 2cm deep, fill so the rice is covered with another 2cm over the top of water). Bring to a boil with a lid on and, when the steam starts to slow (showing that the water has mostly boiled off), take off the heat and leave to stand for 10 mins then serve.
I find that covering with a few teatowels keeps it hot for ages (as in up to an hour or so) so it can be made a bit in advance of whatever else you are cooking it with.
I have been doing it like this for years and years and it is so simple.