Get kids to listen

A

How do you get your kids to listen the first time? My son is four and I feel like I'm failing as a parent. He's a great boy, but sometimes doesn't listen. I know this is probably normal, but then I get frustrated and yell. It seems to be the only way some times. I'm trying so hard to not yell, so I need to retrain my parenting and him. So what steps do you use when parenting?