Hi D.!
I have 3 children that are 4 years and younger. One of the most important pieces of advice I give to new mothers is about sleep habits.
With my first child, we started out rocking him to sleep every night and before naps. Big mistake. Then we HAD to rock him to get him to go to sleep. It would take us over an hour every single night to get him to sleep. And if he woke in the middle of the night, then he would cry until we rocked him to sleep again. We did this until he was about 2 yrs old (a loooong time). Around that time I was getting ready to have our second child and knew that there was no way we would have time to continue doing this. We always had a bedtime routine with my son. That is important so that your child has time to calm down in the evening and then knows that it will soon be time to go to bed. It may include a bath, reading books, etc. We finally transitioned my son to just going to bed on his own (after his routine), but it was not easy.
With our next child, we did things differently. By a few months old, we were able to just put her in her crib, say night night and walk away. It is important that your baby learns to fall asleep on their own, so you should place them in the crib BEFORE they fall asleep. This may take some transition time, but it is a LOT easier to do with an infant than with a toddler. You will not be able to do this with a newborn. When a newborn cries, they need something (food, diaper change, comfort, etc). But eventually, you will be able to let your infant cry for short periods of time to let them learn to sleep on their own (probably around 2 months).
By the way, my pediatrician recommended to us that we put our baby in the crib before he was asleep. We just didn't listen to his advice until we had the second. This makes SUCH a difference.
Also, our first (my son) didn't start sleeping through the night until about 6 months. My second (daughter) slept through the night at 4 months. My third (daughter) slept through at 2 1/2 months. I truely believe that a lot of this had to do with my daughters learning to fall asleep on their own.
Hope this helps! If you need any more specific details on how to transition your baby to sleeping on their own, let me know. I just didn't want this to get any more wordy than it already was...
L.