My first liked her crib, and slept like a dream, right from the day I brought her home, never had a single issue. My second, ugh, I swear the girl could hear my eyelids closing... Funny enough she's my best sleeper now.
Anyway, I'd also made the mistake of letting her learn to fall asleep in my arms, so the conversion to the crib wasn't smooth. When I'd decided I'd needed to correct that, I started out by putting her down in her crib while I puttered about the room, putting laundry away etc, so she got to realize it wasn't a scary place.
At the same time we developed a bedtime routine... same thing, every night; supper, bath, (vanilla in the water, smells like mother's milk and helps them relax) cuddle time and then into bed while still awake. She'd cry, and I'd go visit, soft lights, soft voice, reassuring touches, etc. When she tried to get me to pick her up I would, briefly. I'd hug her and give her a kiss and put her back down and leave the room again. Altogether it took about two weeks to get her into the routine.
My third went straight into the crib from the hospital. By then I was too busy to sit for long.