My first was an awful sleeper, so for survival I just didn't try anything
I just slept with her when she slept, or slept when she destroyed something
My second was awesome, and never wanted help falling alseep... from birth.
Now what I did with my 3rd and 4th, who are my best sleepers... I'm not sure if it really is just their personalities, or what I did, but if it works! Anywhere it says nursing that is DD4... DD3 didn't really care for nursing for comfort from early on.
I would start out laying in their bed nursing them to sleep, then I would do the thing where I'd start nursing them, and then have them come off while I would lay with them. If it didn't work we'd do it again... Once that worked consistently, I would sit beside their bed after they nursed a while (in a chair). Then I would start reading outloud while sitting in the chair (instead of halfway leaning over the bed) and holding their hand or something. Then I didn't touch them at all while I was reading. Then I moved farther away from their bed. This would take a while, but I started when they were right at a year old, and I took a LONG time in between stages. It went much faster with DD3 who didn't want to nurse because *I* was more comfortable moving farther away faster with her. I took longer with Evie because she seemed to need me closer. It took about 6-8 months for me to get to where I could be anywhere in the room for Evie to stay in her bed and fall asleep.