Adding to the PP
I've never been confident as a parent when it comes to sleep... I really only know a few confident parents all are Pacific Islanders who have their babies sleep with them in their arms or siblings arms or relatives arms until they are older. If I'm honest I think 'modern western ideals' are the problems not the sleep. My DH is Finance Manager for an organisation that is parent support for under 2yos... they help with sleep, feeding etc... In a study to look at etnicity and people seeking support it's very Anglo/European specific.
I believe there are 3 big factors in parenting and sleep
1) Children only learn from the opportunities they are given, if we teach them to fall asleep in our arms, then that's how they expect to fall asleep... if we want them to fall asleep in a different way we need to teach them that, and just as them learning to talk, it can take time
2) babies and toddlers seek out exactly what they need to keep their stress levels low, they don't cry to manipulate, they cry to release the stress that is building up in their body, the screaming and snot usually indicates they are stressed ( so they need empathy)
3) little people struggle with change, they find comfort in routines and rituals, change needs to be organised and done with empathy.
It's more a personal thing, but I feel if if a child is upset, saying you're ok is probably sending a mixed message... if we cry we aren't ok... so it's better to say, 'you are confused by the change in routine' 'Mummy is here, I know you are upset'etc... talk about what you observe not what you judge to be happening. (Hugely helpful when they get older)
In terms of everything or steps, how to be confident... if someone can answer that then they'll be and instant millionaire... there really isn't any one size fits all strategy. How to deal with sleep is, personal preference on how much you step in v don't step in... there isn't a magic solution( sadly), Babies change so much in the first few years, Separation Anxiety, teeth, developmental leaps etc IMHO confidence comes from knowing it's almost impossible to get it wrong, and often people don't get it right either, they just manage to get improvements.