"Do everything without complaining or arguing, so that you may become blameless and pure, children of God without fault in a crooked and depraved generation, in which you shine like stars in the universe as you hold out the word of life in order that I may boast on the day of Christ that I did not run or labor for nothing."
Learning to control your tongue in many areas, will serve you well. I wish I learnt that as a kid instead of having to struggle with that as an adult, so be wise and take that habit now. It is so easy to complain, to criticize, to speak down on others when we know better... but I warn you, that habit is hard to break. You are to speak to the least important person in your eyes as if they were the most important... always showing respect and honor.
Remember that one day, they could come to the church and meet you... and the way you talked to them before will have a great deal of importance in their thoughts about the church. If they remember you always being very kind and respectful, they will have a high esteem for the church and you will not be blamed to bring shame to the faith you profess. But if you were rude, proud, impatient, un-thankful, ... you are being a poor example of the gospel and what Jesus has done for you.
So do not complain when you are asked to do something, when you are at a place and you are not served as you think you deserve, or at school with your teachers... but in all give thanks to the Lord. and know, that all those opportunities, are there for you to show Jesus Christ to others.
Love you, and I long for you to work on this, because I know how good it will be for you!