1) Don't fight with your kid about hats, jackets or ties. If he doesn't want to wear them it should be no skin off your nose. He's representing himself not you and anyone who would judge or disqualify your kid based on what he wears to shul is not someone who should be allowed to control you (exception: If it's a school or camp rule, it's superficial, stupid and petty, but you have to support it)
2) Don't fight about hair either. These things don't become a big deal unless you turn them into big deals.
3) If your kid gets in trouble at school your job is to support, defend and advocate for your kid. In the long run your support is better for him and his future development than your ganging up with the school against him. If the kid is wrong and the school has him dead to rights you still have to find an honest way to be on his side. This may be a delicate and difficult dance at times, especially if your kid is a horror show, but home has to be a safe, supportive place. Let the school punish for school infractions. Don't let them make you the bad guy. (And attention school administrators: don't dump this on me; also don't create punishments like detention or Minyan bans that interfere with my schedule. My wife and I work largely to pay your fees. Respect our time)
4) Tell your kids the truth about minhag, midrash, and the rest. Teach the controversy. It won't confuse them. Not in the long run. Over simplifying things and letting kids believe that oversimplification is the final official answer only causes headaches later.
5) Don't use dessert as a reward or punishment and don't harass your kid into eating one more bite. If you want your kid to have a healthy relationship with food put good healthy food on the table and let the kid be guided by his natural hunger without any pushing, prodding, drama, or manipulation from you.
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