SupportBiz lists four ways to be a kind boss.
Be firm, but positive
Each employee will have some positives, even if some of them have a greater number of negatives than the others. Focus on the positive aspects of your employees, and appreciate them for the same. In difficult situations, look at the positive side of things and determine how you can make the best of your circumstances. If any of your employees is at fault, ensure that you tell him/her firmly but kindly to change their erroneous ways, after you tell them what you value about them.
Do not belittle your employees
Do not belittle your employees just because you are the boss, and can afford to do so. Remember that each employee is important to the firm, and treat them equally. Instead of talking down to them, be friendly and approachable so that they readily come to you with their ideas/problems.
Be polite to your employees, even in difficult situations. Always be well-mannered and courteous, minding your manners. Maintain a sense of good humour, and be ready to pay a well-meant compliment.
Give credit when due
Never try to hog the credit of your team mates, but give it when it is due. Sharing credit of good work done with your employees will give them a sense of involvement in the team, not to mention boost their morales.