Communicate.
Always communicate with your staff. The longer you delay information, either to everyone or to one person, the more difficult it will be for your staff to prepare for changes and listen to you as a leader. This also allows you to be transparent with your staff.
Do not assume anything.
Just because someone made an error or mistake once, don't assume they will always do it again. The same goes on the flip side. Just because someone always does good doesn't mean they will always do good. I have had employees go from good to bad, and bad to good.
An employees problems may not be related to the job.
Employees can have problems outside of their work that could affect their work greatly. It takes communication and talking to your staff member one-on-one to learn what that problem is and supporting them in getting better.
Forgive their mistakes.
Just because an employee makes a mistake, you shouldn't note it down in an evaluation or immediately write them up for it. Mistakes happen. I have made mistakes. It's how we learn and grown in our positions. But on the other hand...
Don't ignore multiple mistakes.
If an employee continues to have a problem with a job task, ensure you keep track of those mistakes. Work with the employee to fix the problem. Don't write them up or downgrade them on an evaluation without giving them a chance to improve.
Watch your tone and attitude.
If you walk in the office in a bad mood, everyone will catch that same bad mood. If you are flippant about a decision made by the higher-ups, your staff will be as well. If you walk in with an ego, it will be an immediate turnoff to your staff. Your staff will look to you to see how to act and what is appropriate. If necessary, hide how you truly feel for the good of your unit.
Encourage your staff.
If you see a job promotion someone would be good for, encourage them to take it. Always train your staff to take over your job. Help them grow. Not only is it good for the office, but it will make you look good if you want a promotion yourself.
Visit with your staff.
Go walk around to the various offices or workstations where your staff work. Ask what is going on, have small talk with them, etc. I spend maybe an hour a day doing that. They think I am being nosy, but I am simply getting to know them. They eventually relax and even like it.
Ask for feedback.
Let your staff give feedback on decisions made in the office. They do the job daily - you don't. If you come out with a policy, let you staff review it. They may have a better way of doing things. It doesn't matter how the task is done, as long as it is done in the end and achieves the desired results.
Sick leave.
I still have the problem of assuming someone is lying when they call in sick. It's hard not to think that once you learn how the person is. You can't do that. It makes your staff feel guilty when they get sick and feel like they have to come in. Instead, be understanding. If you see a pattern of excessive sick leave abuse, you can investigate it. Never pry into why someone is sick, otherwise you would be violating law. Talk to them and ask if there is anything you can do to help. Say that you have noticed they have been sick a lot lately and you want to see if you can help them resolve any issues.
Be consistent.
Don't discipline someone for something, but fail to discipline someone else for the exact same thing. The same with your decisions. Don't be all over the board when it comes to the decisions you make. If you are consistent, then your staff will know what to expect from you.
Don't be nit-picky.
Don't sweat the small stuff. There is no point except that you will be suffocating your employees and giving them an excuse to leave the job. Once they see you don't come down on them hard about the small stuff, they won't make mistakes. They will be more relaxed.
Provide feedback.
Don't wait until a yearly evaluation to tell an employee how they are doing. Give them feedback all year long. You don't have to give them a full report. But you can at least say they are doing great in an area or need more work in another area.
Show compassion.
If someone is having a hard time at home, then give them the opportunity to take time off. If they are burnt out, then find something else for them to do. If you show them that you care, then they will be more apt to come to you with future problems.
Learn personalities.
Everyone is different. Just because you can be direct with one employee doesn't mean you can be direct with another employee. Learn how someone reacts to any given situation and adjust accordingly.
Encourage change.
Change happens everywhere, especially in the workplace. You may move locations, laws could affect how you do business, or a downturn in the economy may slow down sales. Don't discourage change when it happens, even if you disagree with it.
Share responsibility.
Often times a job responsibility is given to a supervisor because of lack of staffing, having incompetent staff, etc. However, as times change you will find that you can pass on duties back to your staff. Don't hog all of the important duties to yourself.
Show your flaws.
If you make a mistake or have made a mistake before, and it is relevant to a current situation, then bring it up. This will show your staff you are just as vulnerable to mistakes as they are.
Listen to your staff.
Always give your staff a chance to speak their mind. Maybe they have a good idea or they just want to vent. Stop typing on the keyboard, turn around, and look at them while they talk. They will appreciate it.
Relax.
There are times you have to let your guard down. Share an embarrassing story about yourself. Joke around with your employees. Show that you are a human being as much as being a supervisor.