Massaging the blocked spot. This can be painful, but is very effective, especially if you do this in the hot shower. If you are not able to get into the shower, warm compresses also help. I used one of my old gloves, filled it with rice and microwaved it for 30 sec. You can use any grain like barley or lentils to do the job.
Another great trick for massaging the blockage is to use an electric tooth brush. Turn it on and push the vibrating head into the spot where it hurts the most.
Once massaged, apply sliced potato or cabbage leaves to the affected area. Slice the potato into thin pieces and place them all around the breast. Wear it in your bra for about an hour. I even slept with it. Similar with the cabbage leaves. Take a leaf, beat it with the knife handle to let the juices out, and wear it in your bra.
Of course feed your baby often so he can help unclog the duct.
As a preventative measure I also started taking Lecithin supplements on a daily basis to prevent future blockages.