There is a multitude of classroom management ideas and strategies out there...entire books on this topic. However here are some basic concepts and systems that have worked for me.
Build relationships any way you can! -Greet students when they walk in the door -Stand at the door to give them nuckles/high fives when they leave -Ask them what they did over the weekend -Share appropriate details from your own life -Attend their sporting/extra-curricular events -Be yourself! Show your personality.
Plan engaging activities, and move quickly from one to another! If kids are mis-behaving, your first question should be... was my lesson plan boring? My rule of thumb is that my students need to be doing a new activity every 10 to 15 minutes. The activities themselves should be interactive. Students should be speaking, moving, interacting, etc. It is always better to quit an activity and move on to another before students get bored of it. If you quit an activity and the students groan and say "Aww, we wanted to keep playing", that is a big win! I would much prefer this than students eventually becoming bored or un-engaged with that activity and having behavior problems. You could always come back to that activity another day.
Write the schedule on the board. It is a little thing, but when the schedule is on the board it helps mentally prepare students for what to expect. They know that there is a plan in place for their learning. Writing or sharing learning objectives for the day is also helpful. If students know where you are trying to take them, there is a better chance they will go with you!
Whole class participation reward system. The foreign language classroom can be scary for some students. I expect them to sing, dance, speak, and many other activities that can sometimes be out of their comfort zone. Having some positive encouragement with a whole group reward system can help the class feel like they are all in this together. Generally, each activity I have planned for the day is worth 1-2 points, depending on the activity. After each activity, I add a tally mark to their class's participation points for the day. At the end of the class, I add those points to their score. If we are doing a song, or set of songs for instance, a class may earn an extra point for being extra loud and doing the actions that go with the song. We set goals such as fiestas, etc. that they work towards.
Individual Reward System. Raffle Drawings. Some teachers have great systems of daily or weekly participation points for each student. I have seen awesome rubrics and tracking systems to keep track of who is actively participating in class. Personally, every time I have tried to make participation points a meaningful part of their grade, I have failed to be able to accurately track it during class. Instead, I have moved to awarding students tickets to be placed in our weekly raffle drawing. Students can earn them for positive participation, winning games, etc. We do a raffle each Friday with fun prizes. Students look forward to it and the tickets help provide incentive, and saves my bank account by only giving out 8-10 prizes a week.
Three Strikes and Your Out. When I have a class with a couple of challenging students I sometimes will implement the three strikes policy. If a student is mis-behaving, talking out of turn, etc., I write their name on the board. If they do something again, they get a check by their name. If they do it again, they get another check and need to go to the student responsibility center to make a plan for how they can improve their behavior. If you do not have a student responsibility center in your school, they could go to the hallway, office, etc. to work on their plan. I know this is sort of an "old school" way of handling behavior. However, it is my go-to system if I feel like I have a couple of students who are disrespectful and prone to talking back or arguing. You can write their name on the board and carry right along with your teaching without stopping to reprimand them or have any sort of exchange with them that could lead to an argument or disrupt your teaching.
Post your rules in a visible place, and be consistent. My two class rules/expectations are "treat others the way you want to be treated", and "participate and always have a good attitude". The one thing that can absolutely kill a classroom culture is any sort of student mocking or laughing at others. This should be a 0 tolerance policy. If I ever see any student doing anything remotely un-kind to another, I address it with them immediately and talk it through with them to make sure they understand why it is not acceptable in my classroom. Students need to enter the room and immediately feel safe, valued, and loved. They need to feel free to make mistakes, participate, and most importantly, to be themselves.