I coached five of my kids starting at U6. My last coaching stint was for my youngest daughter's U17 team in WA state.
For practices, use a whistle to get their attention, instead of yelling.
Get a couple of other parents to help, and lay down the rules as to how to communicate with the kids (for other assistant coaches and parent spectators). I used to tell the parents at a pre-season practice/meeting that if they use any profanity, smoke or drink, or are excessively loud/rude, that the game will be stopped until they leave the playing area.
I once had to give an assistant coach the boot from the game and from coaching for the remainder of the season - and made it clear to him that it was him being disciplined, not his son who actually did a much better job and had more fun once his foul-mouthed dad wasn't in his face during the game.
Always have parents bring treats for after the game, and drinks or something like orange slices for half time.
My oldest boy played with a real talented group of kids. Their team played together from U7 - U10 and won every game. They had treats after each game. My next son was two years behind. The parents of his team and decided against after-game refreshments. He started playing on a U6 team, one of only two U6 teams in their league (all the rest were U7). Several of the kids on the U6 team had older siblings on my other son's team. The U6 kids lost every game until the last game of the year.For the last game, I brought treats. They played the other U6 team and WON! As soon as the game was over the whole team came running over, excited that they had won. One of the kids loudly said, "We won, where's the treats?". At that moment we realized that these kids had gone all season long thinking that their team didn't get after game treats because they kept losing.
Learn all the kids names and address them by name or preferred nickname.
Teach them to not use their hands.
Teach them how to protect themselves from a hard kicked ball. Make sure they all have proper equipment.
I had two girls show up for a game wearing soccer shoes without laces because not having laces in your shoes was the fad at the time. The ref didn't catch it and neither did I until on of the went to kick the ball. The ball went about 15 yards and the shoe went about 20.
For the couple of real aggressive kids that are bound to be on the team (likely ones that have watched older siblings play), no headers, no bicycle kicks, no high kicks, no slide tackling.
Practice dribbling the ball. An easy practice drill is to dribble a zigzag through a line of cones. Have them walk or run through the cones as appropriate for their skill level.
Teach them to kick the ball while running. Work on kicking a stationary ball first, then one that is rolling.
Teach them to dribble and kick with either foot. A good drill for that is to stand to the side of the net a couple of yards out (how far depends on age/ability of the kids), and roll the ball across in front of the net a kid runs toward the net. Have them all kick the ball with their left foot for a couple of rounds, and then switch and have them kick with their right foot. It helps if you switch sides of the net at the same time as an extra visual cue to remind them which foot to use.
I worked with three girls on one of my teams (U8 - U12) and emphasized the use of the "weak" foot. All three eventually received state-wide recognition in HS.
Teach them to kick/pass the ball to a teammate.
Teach them the rudiments of throw-ins, corner kicks, and penalty kicks, even if it is only used in practice.
Spread the kids out during the game. Bunch-ball dominated by one or two players doesn't teach them much.
Teach the kids the various positions and help them learn the names of the positions on the field, then give them the chance to play all positions (some may not want to play goalie, so you have to be flexible there).
Above all, teach them to enjoy the game by making it both a learning and fun experience.