I find the heart chakra to be the most mysterious of all the chakras - it refuses to reveal its secrets, just every now and again, it erupts into a flow of compassion.
It's not so much about balance. The heart chakra is really the most important because with it one is able to begin yo feel energy.
To open it more is to just care about others. Do things selflessly. Work is a great place for this. Just find ways to be of service. To help others and then you will see how things begin to change more and more as do those around you.