Use any cup and fill it up to the brim with rice.
Pour rice into a small pot (or rice cooker bowl). Rinse and stir around the rice in cold water. Then pour out the residual water. Repeat 4-5 times or until the residual water becomes clear.
Then re-fill the pot with cold water and let it sit for 30 minutes (This is a key step!)
After 30 minutes, pour out the residual water - try your best not to lose any rice.
Then use the same cup (from Step 1) and fill it to the same level. Pour it into the pot (or rice cooker bowl)
If you have a rice cooker, place the bowl in the cooker and turn it on. You're finished.
If you do not have a rice cooker, simply place a lid on the pot (important!). Then put it on the stove - on high heat and bring it up to a boil.
When you hear the pot boiling, reduce the heat to a medium. Let it cook for 5 minutes (keep lid on).
Then reduce heat to a low. Let it cook for 10 more minutes (keep lid on).
Then turn off the heat. Let it rest for 5 more minutes (keep lid on).
Total cooking time should be roughly 20-25 minutes.