Shush-pat is a great method to use to settle and begin to teach sleep to babies from birth to around 6 months. After 6 months you can use a similar method but may need to change the 'shh' to a sleep phrase or singing as the shh-ing can be annoying to some babies.
We don't PU/PD with babies under 4 months old because it's too overstimulating. Instead we completely calm the baby with Shush-pat. Many parents find that even at 4 months PU/PD can be too stimulating and are having more success using Shush-pat. PU/PD is meant as a last resort after Shush-pat has been tried and there were no results. It's not a cry free method and it does take time to see a change. How to do it?
Swaddle the baby snugly and make sure the room is as dark as you can get it. Lay the baby on his side so you have access to the back. You can use a wedge or a rolled up towel to prop him up.
Patting and shushing is done with a firm pat in the center of the back (like a tick-tock rhythm) and a long, repeated shhhhhhhhhhhhhhh past (not into) the ear. Loudly, like a faucet. Not fast.
Generally you do the patting/shushing in the crib. Though if he cries, you can pick him up, patting and shushing him over your shoulder, until he's completely calm. Then lay him down and keep patting and shushing. Put a hand on his chest, or if the room isn't very dark, shield his eyes from visual stimulation. Try it in the crib but if he wont settle you can pick him up. Keep patting and shushing in the crib for 7 - 10 minutes after he's completely settled and zoning out. Eventually stop shushing. If he cries, shush again while patting and pick up if necessary. Eventually you will get to the point where you are patting and shushing, and he's zoning out and settled in the crib. Then you slow down the patting and shushing, then stop shushing, and keep patting until baby goes to sleep. Stay with him until he's in stage three - deeper into sleep, totally let go, no eye movements, past the "jolt." You may or may not need to be patting still at this point. Some babies will need the patting, some will need the hand on the chest or just your presence. This is the age where they still need you to guide them into sleep, and this is how you do it without accidental parenting.
The key is not to stop just because baby has calmed down, keep it up. And stay with him, don't leave, until he's melted into the crib!
And if 40 - 45 minutes have passed without sleep, feed him and try again. He'll be hungry by then.With babies age 4-6m:
After a while of doing the above (this will vary from baby to baby) you would work on leaving the room. Young babies find it hard to self soothe so it's better to wait till they are in deep sleep (instead of leaving the room and having to come back every 10 minutes to settle again).
At first you stay with the baby till he is in deep sleep, after a while you leave the room when baby just falls asleep and then you work on leaving the room when you lay him down in the crib.
***Some babies find the patting stimulating, especially touchies. You can adjust Shush-pat to your and your baby's abilities and needs. You can try laying them on their back and not on their side, putting your hand over their shoulder or tummy instead of the patting. The key is to be consistent with the way you are using Shush-pat.
Some would also find the picking up too stimulating, so if you notice it's easier to settle your baby only in the crib then do that and only pick up when baby is very upset. You are always there with him so he is never left to cry alone.
For further information:Can a baby be too old for sh-pat? Why are Shush Pat and PU/PD not props? Sleep interviews with Tracy