Ask anyone who played youth sports reflect on something their parent said to them after a game or some sports incident with their parents and I guarantee almost every person will have a story for you. Parents have more influence on their kids in sports than any coach or trainer will ever have.
It's shocking how intense some youth soccer games can get and often times parents cannot wait until their kid gets across the field so they can talk about the game! Next time your child plays in a game notice how quick you are to discuss the game when its over. While you may have some great advice to give, your #1 job is to support and encourage. This does not mean that you cannot discuss the game, just be careful about how you approach it. Instead of offering up your opinion, begin the conversation with, "Good hustle today! How did you think the game went?" This will allow the kids to reflect on how they did and open up the conversation in a positive, encouraging way.
Pick and choose your moments. Wait for the kids to ask you what you think. Let the coaches do the coaching. I guarantee you will always get more out of your kids and your kids will enjoy themselves the most when you play the primary role of the encourager/supporter.