This is a great question and a very popular one for us new or student teachers. I am going to throw a little feedback here but mainly wanted to thank you for posting this, I look foward to following this and hopefully seeing more input eventually.
First off, in my opinion, the key is not necessarily to keep the under control while keeping them engaged, I think those two things go hand in hand. What I mean is, if you have a trouble classroom one of the most important things you can do is keep them engaged, a bored class is a disruptive class. Try to find out what their interests are and work them into the lessons when applicable. I would focus your energy on making engaging lessons with multiple transitions and at least one activity that allows them some movement and/or group/pair conversation. Multiple resources point to students having the attention span of their age in minutes, try not to have them doing one thing for too long and be sure to give them a schedule or plan for the day, preferably somewhere in writing, to help smooth over those transitions. I notice when I dont do these things in my lesson plans I end up working more on classroom management that day than most.
In addition to that make sure you have clear and consistent classroom norms and even though I dont do this, I would suggest having them up somewhere where studetns can see them, gives you something to reference when norms are not being folllowed. Some teachers really like having the students make the norms on a big poster (but teacher gets to add some too) and then everybody signs it, gives an image of accountability. My class gets 3 participation/professionalism points every day and if they are being disruptive or unprofessional or dont follow one of the norms, then I remove a point, this techniqe works better on students who actually care about their grade but it acts as a quick way for them to see consequences for their actions.
Lastly relationship building has been my biggest go to for management issues for individual students. Take the time and make the effort to really know a student, this strategy will look different for every student, and you often find the behaviors of that student improve.
Good luck with your classroom management, I hope you get some more feedback soon.