Well I guess every baby is different and will respond to different things, so it was a matter of figuring out what DD responded to and then coming up with a little routine and being verrrrrry consistent; and also making a decision with myself that I would not get cross with her whatever happened - that I would just stay calm and stick with the routine until I saw a least some results. I didn't do CC or CIO but only because she was too young to do it and I couldn't wait long enough for her to get old enough!
My method involved throwing every sleep prop in the book at DD apart from the boob - so, rocking in pram, white noise, comforter, and a special sleeptime song that was soothing and was only ever played at naptime. The week I decided to it I made all of the naps indoor naps (she had no problem dozing off straight away outside in the fresh air!).
Step 1. Zip DD into her snowsuit so she thinks we're going for a walk.
Step 2. Turn on the white noise (extractor fan!) and the sleep song
Step 3. Put her in pram with her comforter and rock it until she gave in and fell asleep.
Note: There would usually be a bit of tired whinging, but no full-on crying. I figured out that she liked to put her face in her comforter just before she fell asleep, so once I saw her doing that I knew she was nearly there.
Step 4. Once DD is asleep, STOP ROCKING THE PRAM. V. important. (Previously I would sit there rocking the pram with my foot while MNing or making lunch because I was so terrified she'd wake up. ) If she woke up, I would rock her back, but once she was asleep I'd stop rocking.
Step 5. After a week or so of this, put DD in the pram at naptime with the white noise, song, and comforter, and let her put herself to sleep. Again, this took a bit of time and whinging, but no full-on crying.
And actually, I was really happy with that. But when I did want her to sleep in her cot as opposed to sleeping in the pram in the kitchen, I swopped the snowsuit for a sleeping bag (she was still being zipped into something so it wasn't much of a leap) and kept the white noise, song, and comforter. I sat by her cot while she grizzled, either holding her hand and jiggling it, or jiggling her bum. Once she was asleep I tiptoed out and left the song playing on a loop. But dropped the song easily enough after about a week. I kept the white noise for much longer.
See, told you it was convoluted :) If you're breastfeeding, as a very first step to all this, you might think about introducing a comforter and keeping it with you while he's feeding so that it picks up your smell.