I always use cold leftover rice that I've left in the fridge overnight as it has had the chance to firm up. Using cold rice makes it easier to separate when frying and decreases the chances of your fried rice turning out mushy. I've tried this with freshly cooked rice before and it gets sticky and mushy quickly. I always make my rice the day before. If you don't have leftover rice, you can try to prepare the rice beforehand and then spread it out on a sheet pan so it can cool quickly in the fridge for an hour or so.