1: You are there to have fun, watch some (hopefully) fun games and support and cheer on your kid and the team.
2: Accept the fact that you know HS Football, but not soccer so much. Any dolt can see that passing over the top to the speedster will result in a chance to score, but is that what the coach wants? Is that developing the team or just a few players? Maybe the coach wants to see ball movement, possession, switching the field, back passes, etc. You ain't the coach, you are a parent. Don't coach from the sideline because you don't know the game plan.
3: Winning is fun, but winning isn't necessarily the measure of getting your monies worth. Your kid is playing club soccer, so hopefully that means the kid has some talent. The goal (pun intended) is to develop your kids talent to the point that they move to the next level and the next ... keep on developing and maybe a scholarship awaits. Winning is a nice byproduct, but not the measure of success in youth sports, so don't get all riled up about wins and losses ... this isn't Texas HS football where jobs are lost.
4. Quietly laugh, chuckle and make fun of the Dad's and Mom's that think screaming and yelling and complaining about this or that is going to have any impact on the game ... other than seriously annoying the players, coaches, refs, and the other parents.
5. Accept that the Referee is going to make bad calls.
6. Accept that your child will make mistakes.
7. Accept that your child's teammates will make mistakes.
8. After the game, tell them how proud you are of how they played. Focus on what they did right. They know what they did wrong (trust me they know). Let the coach give them the constructive criticism. After the game, take them for a soda and pizza. [P.S. I know you are going to fail on this one, we all do ... I do it every game, but dammit I'm trying my best ... just need the boy to have a clean sheet every game.]
9: Advanced Level Soccer Parenting: Take the Referee courses (free). Go through every single video for the Grade 8 and Grade 7 Referee courses. Learn first hand that refereeing a Soccer games is unlike anything you are used too. Appreciate that Soccer Referee's have wide latitude to "not call" a foul due to advantage or because the foul is "trifling." Seriously, watch the official course materials and answer the questions.
https://www.ussoccer.com/Referees/Resource-Center/Online-Training/Grade-8-Referee-Course.aspx
https://www.ussoccer.com/Referees/Resource-Center/Online-Training/Grade-7-Referee-Course.aspx