Have you eaten (rice) yet?
Plenty of instruction here on how to cook perfect, tender plain rice. Mostly for medium or long grain rice, so I'll just slip in some more information here. Regardless of whether you wash and then drain the rice, the proportions remain the same. See Grain Recipes for recipes which are more involved sides or are dishes in and of themselves, rather than a staple. Keep in mind, some rice will never run clear no matter how much you wash it. Black rice comes to mind. Also, nutrient added rice is not intended to be rinsed as the vitamins are added as a dust. If it's enriched or fortified, it's likely meant not to be washed.
Soaking rice in cold water prior to cooking it is never a bad idea. It really does help it cook more evenly. Also, some recipes strongly recommend or even require it.
Polished long grain which includes Basmati rice, Jasmine Rice, etc. and medium grain rice.: 2c. water for the first cup of rice; 1.5c. water for each additional cup of rice.
Polished short grain which includes Arborio rice (for Risotto), Sushi Rice, glutinous rice or sticky rice, etc.: 1.5c. water for the first cup of rice; 1c. water for each additional cup of rice. Note, depending on which variety you purchase, your results will vary greatly. There's plenty of specific information over at sushi rice for that particular culinary staple. Risotto, of course, is not made with cooked rice. In Thai cooking coconut rice is made with pre-cooked sticky rice, which is a consideration if going that route. I always soak sticky rice for at least an hour prior to cooking it, ideally overnight.
Brown rice, black rice, red rice, etc. (ie. any rice with the bran intact), the same amount of water depending on if it's a long or short grained variety, plus an extra half cup and additional cooking time. The bran makes it more difficult for the rice to absorb liquid, so soaking it in advance is a good idea if you have the time.
If cooking a mixture of brown rice and white rice, start the brown rice first and let it simmer for about 10 minutes. Then add the white rice and additional water, give a quick stir to combine, and start the process over again. When cooking brown rice in your rice cooker, cook it through one cycle and when it pops to "keep warm" add half a cup of water to the cooker (a bit more if it's very full) and cook for another cycle. It should be done by then.
Wild rice which isn't wild and isn't rice. It behaves more like brown rice because the bran is still intact. According to the box of wild rice sitting before me, it recommends 1.5c. water per third cup of wild rice and recommends 45-50min. for firmer rice, and 60-65min. for tender rice. Again, you could start wild rice, cook it until there's only about 20min. left to its cooking time and then add in raw white rice and water and let them cook together.
Persian rice is a staple about which a friend who's half Iranian has waxed most poetic. It's much more time consuming than the above and results in perfect, fluffy grains which are firm and then tenderly dissolve upon chewing. I present it here because not everyone eats their rice sticky (as in, sticking to itself, not as in glutinous rice), after all.
3 cups long grain white rice, basmati is the best readily available variety to use
1/2 cup butter
1/4 teaspoon salt
2 quarts water
1 cup water
Several hours before, agitate and rinse the rice very well until water runs clear. Soak the rice in cold water for as much as overnight or as little as an hour. The longer, the better.
Bring 2 quarts of water and the salt to a boil and par-cook the rice uncovered and stirring frequently for about ten minutes. Drain the rice and rinse with warm water so it stops cooking and to wash away more starch.
Meanwhile, in a heavy bottomed pot with a close fitting lid, melt about half the butter.
Gently stir in the rice and mix it with the butter just to combine, adding any other flavoring agents (saffron for example) and the water at the same time. Scrape the rice into a mound and dot the top with the remaining butter.
Cover the pot with a clean towel and tightly cover with the lid. Tie the towel to the knob on the lid to prevent it from flopping down and catching on fire.
Punch the heat to high for just a minute to kick start it back up again, and then turn the burner down to low and cook for 25-30min. The bottom of the pot should form a crunchy, crispy, buttery layer of rice which folks will fight over, and the rest of the rice will be nutty, and perfectly loose and tender. Serve immediately, and turn the crust out on top so it stays crunchy.
Recipe adapted from this recipe and this fantastic article