Anyone care to share about how you sleep train your baby? Where did you get the method from? And how old did you start training your baby?

Background: my little one is 3 months old, and need to be nursed to sleep. He couldnt sleep more than 30mins in the day without waking up and fuss for my breast, and he would suckle for a few seconds and went back to sleep. But at night he would nurse to sleep and wake up 3 - 4 hourly. So I'm stuck on my bed to nurse him in the day, a walking pacifier.

I know its a bad habit to let him associate sleep with nursing, but how can ì break this association?