My nearly 5 month old DS responded well to Jo Tantum's 'spaced soothing' technique. You put your LO in their cot at nap time (best to start in the day), kiss and settle them, say 'sleepy time now' or your own chosen sleep cue words, and firmly leave. If they protest/quack/grizzle/cry a bit, leave them for one minute and then go and settle them so they are still awake but calm (in the cot if possible, replace dummy, stroke brow/down nose gently, reassure). Say your sleep cue phrase in a soft neutral voice and leave. And repeat until they have fallen asleep. Always leave before they have nodded off so they experience falling asleep on their own.
The advice is to leave them for increasing increments of time, up to five minutes. I don't want to extend it though so only ever leave him for a minute or less sometimes. Lots of mums seem to naturally give their babies a minute to see if they're winding down, this method gives me permission to try that (am a very soft touch!). It isn't a very long time, isn't long enough for your baby to get really distressed.
So it's like a miniature CC, only the advice is if your LO gets genuinely upset you stop the spaced soothing and go to them immediately. And try again when they are calm. Also, she says to make sure to check for wind or hunger beforehand.
So I feel it's quite a clear gentle way of responding to your baby, but giving them a bit of space too.
It made a big difference to DS, he was much more confident in his cot and more well rested in the day. Also he would occasionally self-settle after one 45 min sleep cycle and nap for an hour and a half, which he couldn't before.
It's all gone to pot now though, because he has a terrible cold, the poor little beauty, so am back having to feed him to sleep for naps and at night. Sigh. But he is poorly, he needs the extra comfort at the moment. I will go back to the spaced soothing when he's well again.
HTH