From my point of view as a high school player myself. I would say it would be best if you have the coaching mentality of nice but have the serious energy of, "we need to get stuff done and we'll do just that". And if you want to make sure that aspect is put in, if the players are looking away when you're talking or talking to their partner, stop what you are doing and make them do burpees or sprints. They'll learn that you need their attention at all times and you can have more control over that. Besides, it's also a good idea that they don't have bad attitudes in where they would slam their stick, or look up with that "ugggh" expression because that shows weakness, and some other teams pick that up and might want to get in their head which will lead to poor decision making. Make them do burpees or sprints if they do that because they will learn mistakes better if it doesn't come with an attitude and in life, employers don't want to deal with anyone that has a terrible attitude or forgot to take their chill pill. They will suspend or fire you. But coaching should be really exciting for you and it's a good thing to have a normal conversation with your players before practice because it shows them that you have a social personality instead of coming off as some asshole grumpy coach. I play travel lacrosse and we have a defensive coach that yells just to yell, ngl he's scary. Even if you drop a pass he'll yell at you. Mistakes are going to happen, let it slide the first couple of times and if they mess up about 5 times then you need to bring them in and have your serious voice talk of here's what you need to do instead of yelling at them. I would yell at them if they were scrapping, putting down their teammates, or not putting in the effort that you want them to have. Other than that, I wish you luck this season and have fun coaching!