Never respond negatively. It will cause tension and resentment in the office and cause workers lower down the ladder to band together. They'll talk about you when you aren't there. If you don't listen to them, it will get around. If you are mean to them, it will get around.
Be clear. Make a game plan before you assign tasks. You should know the ins and outs of every facet of your operation, and you definitely should know how to explain it to someone else clearly. If someone makes an error, assume you did not clarify something well enough. You should have a clear idea of how long it will take someone to finish a task, what the task entails, and what task the person will be doing next. Make sure you have all the necessary supplies and that no one is caught sitting without anything to do. Form teams and get things done.
Never waste their time. People know when they aren't doing something useful, and it irritates them. No one ever wants to feel like his or her job isn't important. It is degrading and can be almost hurtful. Always make sure a job has a significant purpose.
Know who is on your team. Make sure you are aware of what people can do before you can hire them, and make sure you know their limits. There is nothing wrong with an excessively long interview or taking a second interview. Take all the time you need to make sure that your workers fit together and that they are willing to listen to you and do what you need.
Do not hire people if you aren't positive they are right for the position. If you hired someone that is always complaining about tasks and not completing things on time, then you are to blame. Get them into shape, or get rid of them. It is your responsibility to make sure things run smoothly. Do not antagonize them, but be constantly aware of what they are doing. Remind them how to do things right, have people check on them, and if things still aren't getting done, then ask them to leave. Firing someone should be a last resort. It may get people in line, but you definitely wont create a happy working atmosphere.
It should never be considered "work." I don't mean that your job should be a constant party where nothing goes wrong, but people do not like working. It's a fact. Let people have 15 minutes to chat. Have casual Fridays, bring in the bagels once a week, and make sure there is always coffee. People will enjoy coming to work a lot more and will be more receptive to your demands if they actually enjoy your company. Happy workers get work done. Upset workers drag their heels. Taking a half hour out of the work day every once and a while to have a potluck will not set you back much. The work will still be there, but at least you and your staff will have had the chance to calm down and relax with their friends.