Classroom Library Organization Tips

So I have not been able to decide how I want to organize all of my books. I can’t decide if I want to separate the books I will use for lessons and the books I will put out for the kids, or if I just want to leave them all the way they are (organized by theme, but altogether in one area). I also don’t know how to have them browse. Currently I just have two shelves that I put books on and they get 2-3 at a time. My kids have book boxes as well so I don’t know how to have them use the library vs. their book boxes that have leveled readers in them.
How do YOU organize your classroom library? I would appreciate any tips/ideas everyone has. Even let me know what hasn’t worked and why it didn’t work for you! I look forward to hearing from all of you lovely teachers!