A couple of things come to mind right away:
1. Introspection. Another word might be self-awareness. Think about your actions for a given time period, a particular group, or a specific person. Reflect on whether or not you think you acted appropriately as a leader and what you might do differently or better in the future. The introspection I'm speaking about should typically be positive. The goal isn't to beat yourself up or to get mad about how someone else acted or treated you. It's about your continuous self-improvement.
2. Solicit feedback. Since perception is reality, our self-perceptions are important. Way more important, though, are the perceptions of those around you...your boss, your team members, your colleagues. Ask them how you're doing and what you can do better. Consider these:
~When you have a 1:1 conversation with a team member and give your feedback and direction, take a few minutes to let them provide feedback for you on what they think you can be doing better. This one definitely needs to have a trusting foundation or your team member will never completely open up, fearing retribution of some kind.Bottom line: YOU are ultimately responsible for making yourself a better person, employee and leader. To a large extent, you control your destiny. If processes are not in place to help you be better, go seek them out. It's up to you.
~Find a mentor. This person should NOT be your boss. I've had several bosses who've told me, "well, I mentor you, myself". No they don't. They guide and direct in a vertical relationship. What they do is totally appropriate, but it is not mentoring. In a mentoring relationship with a colleague or some other person you trust, it should be a horizontal relationship and you ought to be able to talk about anything and that includes your boss (how could you not talk about your relationship with your boss, you know?). It's fine for your boss to help you find a mentor, but this should be a confidential relationship where the boss is not involved (of course, confidentiality has it's limits and the expectations should be understood when the mentoring relationship starts).
~Ask your boss. Hopefully, you have a boss who values 1:1 regular discussions with you and you already are receiving thoughtful, constructive feedback already. If you're not, ask for it. I asked a boss one time what I could do better (we had no evaluation or feedback system in place at all). She said she had nothing to tell me and that I was doing great. The problem was that she had no problem telling me how I'd screwed up during the course of business. I think the problem was that she didn't know how to give me feedback so she avoided it. If you have regular feedback and guidance sessions with your boss, you should never be surprised come evaluation time (hopefully you have one). It should just be the culmination of all the work you've done with your boss throughout the evaluation period.