Hi Angeldog,
I use dummies, comforters and Rapid Return.
I gave DD a dummy for sleep time from 1 month old. Initially she wasn't too interested by did suck a bit before sleeping.
I also got her 2 comforters (we have Kraig the Comforter, a small white thing from John Lewis and Karoline the comforter, a fleecy thing from Mamas & Papas...).
Initially she'd just suck the dummy to settle herself. As she's gotten older she is loving her comforters. Every time I put her down for nap or for bed time she rolls around cuddling them and talks to them - very funny and there are always big smiles for them :-))
Before taking her upstairs for naps, I'd always say: "naptime" so she could learn to anticipate the change coming.
for a while I'd have to stay in the in the room for 10 and hold her hand or just stand by her cot so she could see me. Then I would say: "naptime, settle yourself, naptime" and then leave the room and go downstairs. And then if she started to cry I'd go upstairs and shhs her without picking her up.
And for a couple of weeks I was up and down the stairs constantly and it would have been easy to give up. She was also testing me a lot and would do a sort of a fake pretend cry to get me to come and she'd stop to listen for my footsteps - cheeky girl.
But after a couple of weeks she understood that at naptime she stays in her room but muumy will come whenever you need her.
I thought it was important for her to feel secure that I'd be there even though she initally tested it but it helps with sleeping at night too because she knows she can just call and I'll come. I think as she feels secure she doesn't call for me.
Also felt that comforters were helpful as were dummies (DD loved the boob and now dummies). I know some mothers feel dummies are inappropriate and if you do you can always use comforters.
As I said its worth having scheduled naptime. Your DCs know when its sleepy time and will settle easily. ANd you avoid having a tired waily baby which makes you feel like a better mother (and a lot more sane!).
I am very keen that DD should NEVER EVER be left to cry at all and I could never do controlled crying (I end up doing the crying listening to my precious girl breaking her heart) and my implementing scheduled naptime and bed time as a routine, I've avoiding any form of crying. Rapid Return may sound like a pain but the upside is no wailing (or broken hearts) and you get fit running up and down the stairs .
I know there are lots of theories and lots of people tell you so many things it makes your head spin. So I hope something works for you all.
Spoke to a friend of mine who is currently using a nap routine (for a 6 month old) of 3 naps of 45mins (around 9, 1 and 4). And apparently that works really well too.