Are you ready for this... apologies in advance for the length!
I started off getting to know his sleep cue's. Once I spotted them I would start to feed him downstairs (whether he was hungry or not, he would feed!), then as he got drowsy we would go up to the nursery and continue the feed. Whilst feeding I would rock the chair (a cosatto rocking chair - the best thing we bought!) and sing softly to him. Once asleep I would put him in his cot. At first he would sleep for 15 mins, but after doing the same routine 3-4 times a day, the period of sleep would increase. If he woke up when I put him in his cot, I would rock and sing again, but not feed.
Once this was going well I would do the whole feed downstairs, then go to the nursery for rocking and singing. Then put him in his cot when he was asleep.
Eventually the sleep association became going to the nursery and rocking and singing, so he no longer required the feed.
Then, he got so used to the whole sleep routine I could put him in his cot half asleep and he would get himself off to sleep.
It took time, but it has worked really well for us. The first few days were the hardest as it didn't feel like it was working - even though it was, albeit slowly.
It enabled ds to sleep better in the day, get to sleep at night, sleep through the night, and it set him up to get himself off to sleep.
Hope this makes sense!!