Wrapping worked well for us, and was the advice from the paediatrician too. I found that he would start crying when we first put him down, but they were sort of sleep screams - he'd make these noises for about 5 mins then go to sleep. I used to sit and watch the clock and if he wasn't asleep in 5 mins, try something else, but after a while it was consistent and he'd fall asleep faster and faster.

Other advice that helped us was making sure he wasn't too hot, and getting the room dark and quiet.