My first born (son) had a really hard time sleeping, my daughters are the ones who would reach for their crib. I always nursed them all, rocking or not, and they usually fell asleep nursing before I put them down. The girls could be layed down awake after nursing, unless they were teething, but I spent so much of my time putting my son down (then he took such short naps!)
With my son, I had to come up with a complex series of movements to transfer him because he would always wake up crying when I layed him down. I tried walking him back to sleep, but he was so big I always ended up exhausted before he fell into a deep sleep. What worked? Swaddling worked (not just for newborns) with a really big, stretchy blanket. When he was asleep, I'd hold him close, leaning way down (moving very slowly) like some other moms have said, then I'd hold his chest down releasing pressure slowly. I'd hold my hand just over his chest for a moment, slowly bringing my arm down. I'd take a step or 2, then pause, a couple of steps, then pause, until I was out of the room. If I left too fast, somehow he could feel it & I'd have to start all over again. I also swear that my thoughts made a difference. I could always leave sooner if I was thinking about doing whatever I needed to do to get him to sleep. Whenever I was thinking, "Hurry up! Mama needs to ____!" that's when he would wake up crying. I also had a window of time to transfer him. If I held him too long, he wouldn't stay asleep when I tried moving him to his bed.
My son grew very large, very fast. We moved him out of the crib onto the crib mattress on the floor shortly after he turned one year because the easiest way to get him to nap was to nurse side-lying & then sneak very slooowwly away.
What worked with the girls? I hummed the same lullaby every time I wanted them to sleep. (And I still do, the little one is 1 1/2 yrs.) I also paid attention to what they liked & tried using that item for a comfort item, giving it to them before each sleep. (One person I heard about used a pillowcase, so if they left the comfort item anywhere, they could always get another pillowcase.) My oldest still loves his bear blanket at 6 y.o. My youngest prefers a playsilk. I've been calling it Happy Nappy Time with my youngest. When she's teething & clinging to me, I whisper that she needs to sleep & I will come back to get her when she wakes up. Somehow that helps her release from me & she'll sleep. (There's clove oil to rub on her gums for teething that helps also.) When she's fussed about laying down, sometimes she's been soothed just by standing by the crib patting her back.
My sister figured out her first born needed to sleep upright, so she layed him in a 2nd infant car seat with the straps taken off that was sitting in his crib. Then she figured out that he wanted it really dark in his room. I know you'll figure out what works for your kiddo.