In the long run, we can see that the people who stand out as great people, are the ones who put the common good before their own good. Although we can't all be a Mother Teresa or a Ghandi, this same idea can bring about positive change in our personal daily lives. That is, when we focus on helping others instead of always putting ourselves first, everyone feels better.
I believe more people do need to put the common good ahead of their own personal interests. This is called social responsibility and it was quite common when people lived in smaller communities. Our greed and search for self interest has done nothing but harm our communities and the people that are in them.
This world can sometimes seem very hostile to a person's private interests that people are apt to think that they need to protect their own interests above all others, because no one else will. This form of thinking can be shown to be faulty if a person recognizes that they themselves are a part of the common good, so working for the common good also includes working for their own good.
I think we would accomplish a lot if we were ever able to step outside of our own personal spaces and join together for the common good. Even if each person could donate a day a month to improve a blighted area, or help repair a rundown house, or help an elderly neighbor - there is so much that we could accomplish.
I firmly disagree with the idea that people should put the common good (or whatever is defined by it) before their own self-interest. This is for several reasons:
1. Practically, the use of the "common good" has often led to corruption and a decline in freedom. Common examples of the "common good" being used in a corrupt way is during the Soviet regime and the situation in North Korea. Again, it generally decreases freedom as inspiration from the common good typically leaves more people feeling justified to intrude on the freedom and rights of other people in order to promote the "common good".
2. Working for the "common good" typically decreases the thinking and intellectual activity of people. Because promotion of the "common good" typically leaves people feeling justified to be unpleasant to those who don't promote the same goals, and thus leaves people accepting social standards without a thought to whether these actions actual do increase welfare. Such examples are that of Fair Trade and the minimum-wage, which typically decreases the welfare of both the average man and the poor (the former by mainly focusing on those who meat their standards, who tend to be wealthier farmers. The latter by creating a shortage of demand, thus causing otherwise employed poor individuals to become unemployed and thus poorer).
A famous quote that defends this is "Virtue is more to be feared than vice, because its excesses are not subject to the regulation of conscience."