Please give me tips to stop my baby's thumb sucking habit...

Don’t make a serious issue of it. Psychologist Cliff Arnall says: "Generally thumb sucking isn't a big deal but it can be easily turned into one if it becomes the regular centre of attention in the family. "Hence talking about it at the dinner table, and specifically its eradication, is not going to help change the behaviour. Indeed this approach may bed down and consolidate the thumb sucking behaviour further. "I'd advocate a gentle and playful approach. Hence playing a game where every time a thumb is sucked Daddy or Mummy will start hopping on one leg. This approach makes it far easier to look at making a behavioural change." http://www.webmd.boots.com/children/guide/breaking-thumb-sucking-habit?page=2