Should parents prevent their children from making mistakes, or should they allow them to learn from their mistakes?

I prefer my parents to help me to realize my mistakes because parents tend to be experienced; with their help, kids may correct mistakes quickly and achieve better results. 

I remember when I learned English in my childhood, I couldn't remember words clearly, and I felt depressed quite often. Knowing this, my parents gave the guidance, telling me once I learned some new words, what I should do is to review them as many times as possible instead of just reciting them once; reciting once without reviewing is the typical mistake when learning a language. Afterward, when I learned some new words, I paid much attention to how many times I have reviewed them. Then I could remember English words well. Thanks to my parents' help, or else I may not learn English so fluently.