Family, friends and strangers. Once home, (and away from the professionals), new opinions and advice will usually come from your family, friends, neighbours (and even strangers - usually other mothers!) Fathers may also receive advice from their friends, relatives and peers when they return to work.
People who give advice to new parents usually see it as 'good', because what they suggest 'worked for them' (and therefore should work for you and your baby). However, there are very few babies (if any) that can emulate another baby, and parenting styles are as individual as you are. Therefore, infant care strategies that worked for grandparents, sisters, cousins, friends or the butcher, may not necessarily work for you.
If the advice you are given is not working, (or doesn't feel right), it doesn't mean you are not parenting correctly. It is simply a matter of the suggestion not being right for you and your baby. Advice (from wherever it comes) is usually well intentioned, but will almost exclusively be based on the advisor's own personal experiences (or what was done in the 1970's). These may be similar to your experiences, or millions of miles away from what you are going through.
Becoming a parent can also bring up issues surrounding your own relationship with your parents. It may be that you want to be as 'good as they were' or determined to do it all differently. If you don't have much contact with your parents, (or your parents have died) then having a new baby can also bring up many unexpected feelings, such as grief or abandonment.
How you are feeling about your parents can influence how you approach your own parenting. It can sometimes shape the way you do things, or provoke extreme reactions if Grandma or Pop starts giving advice. You may feel you are being scrutinised or judged, or you may rely on their guidance with love and gratitude.