There is more than likely always going to be some kind of tension on a job due to the varied personalities that your employees all have. They have different interests and lifestyles and consequently are not always going to see eye to eye. As an employer it is your job to try and help your employees to find common ground and get along. It is pretty much essential for the success of your business that people who work for you at least get along during work hours.
You should try and teach all of your employees that they need to learn how to communicate with one another in an effective manner and that they need to do so without causing any kind of conflict at work. Teach them how to talk over their problems with each other by using nice tones and make sure to choose their words wisely without acting as if they are accusing someone of something. Make sure that they understand just how important listening is.
As trivial this may sound, allow your employees to be able to label the office supplies that they use at their desk with their names. A lot of complaints that come from employees is that their stuff from their work area is always disappearing. By doing this, it's going to cut down on the temptation for other employees to walk away with others office supplies.
Make sure to put limits on how loud any employee can have music at their work area. Remember if you allow music, not everyone likes the same music so it's important that the volume of the music be at a level that will not disturb others in the immediate vicinity.
Make sure that you let employees know that they shouldn't all stand around a person's work area having a conversation about something dealing with work or not dealing with work. There could be a possibility that the person they are all huddled around may not care to be involved in the conversation and might rather just be left alone so they can work in peace. Besides this it also means less work is getting done in your office.
Another thing you might want to enforce is that all employees need to eat their lunches in the break room or somewhere else besides at their desk. After all what they are eating may not smell very good to someone else who might be sitting nearby.
It's perfectly OK to allow your employees to decorate their work area with personal items but you also need to make sure that they are limited to how much they decorate and what they decorate it with. Understand that to some people a lot of non-work stuff might be a distraction to them.
Note: It is important to make sure that you pay close attention to how your employees might be responding to one another. If you notice something that might look like a disagreement you may need to intervene and have a meeting with them to see how the situation can be better handled.