As a new father this is the one aspect that has been the most crucial to learn. My son is a great sleeper. Has been since he was 2 months old. I know I know, I’m lucky. My wife and I did a lot to make this possible. From getting a good nightly routine to feeding him most of his calories during the day to having a good wake, eat, sleep window schedule during the day to the technology we employ. Sound machines are a must. Black out curtains, yup. His own room, check. Also, keeping him awake until its nap time is key. He sleeps 12 hours a night with a slight dream feeding (20 minutes) that he rarely wakes up for and never impedes his sleep.
Crying still happens. That’s where having his own room works out so well. If that’s not possible, yikes… that’s hard. We’re fortunate that he has his own room AND it’s on the top floor of the house so we can be downstairs and just let him cry without feeling the need to jump up every time to get him. We’ve accepted the fact he’s going to be fussy sometimes. That doesn’t mean we just let him cry himself to sleep – that is not a good habit either. However, we give him enough time alone to sort it out, and he does. Even if he’s frantically crying (usually because he’s overtired) he conks out within 5 minutes, typically in much less time.
All that to say, accept the crying.