It sounds like you really care, and you're struggling with balancing the good-cop, bad-cop both with the same face, deal. My advice? Use the carrot more than the stick. I've worked for people in my life that I'd get one over on if I could, because screw them, that's why, and I've worked for people that if I felt like I hadn't done my best, I should be truly ashamed of myself. Guess who I worked harder for? Hint: It wasn't the one who carried the biggest stick.
Above it all, be fair. Noone respects anyone who isn't fair, and on the same hand, it's very hard to truly remain at odds with someone when it's plain to see that they are treating their team RIGHT, without exception or favoritism.
My boss? Currently? I have worked for her for almost a year and a half. I have seen her on less than a dozen occasions, and most of that was incidental (we passed each other in the hall, we went to the same meeting, etc.). She has said 2 sentences to me that were positive the entire time I've been at my job. She has, however, treated me flawlessly fair. She has respected me. She has ALWAYS gone to bat for my team, and I am very pleased to work for her. My last good boss was very similar. She never came out onto the unit when I was around hardly, but when she did, if she had something negative to say, it followed only after a long discourse of positive, and she was ALWAYS trying to teach and better someone when she gave them a hard pill to swallow. She always used it as a teaching moment, and write-ups or punishment as it were, was meted out only at the bare minimum of institutional demand. As in, she would get reprimanded for not doing at least what she did in punitive action.
I am of the opinion that a government which governs least, governs best, and thats how I like my bosses. Leave me alone. Don't bother me. Don't have to really praise me or do things FOR me, either. You hired me because I'm competent and good at what I do, and am very self-directed and effective. SO let me DO. And my boss has, and does. That is how you make ME happy. And you're going to have to learn what makes each and every one of your employees happy. The paperwork is the cake of your job. It's the peopling that is the chore.