My second cooking job was working the fryer station. On opening night, my chef noticed I was under-seasoning the fries. I increased the salt, yet it still wasn't enough. He finally broke down and said, "I won't be happy until someone sends an order back for being too salty!" Five minutes later, an order came back.
I'm not advocating over-seasoning your food, but it's important to realize that salt is a key component to balancing flavors. Don't be afraid to use it, but learn when to back off. It's tricky, but you can learn how to do it well here.