We do exactly the same thing every time and 19 times out of 20 dd (9m0) settleswithout a peep. The key thing for me is not just what we're doing as the words I am saying. I'm sure she picks up on the verbal cues. The routine is:
Nappy change
Then I start talking her through the routine in a slightly sinister drone low voice "it's naptime darling, so what do we do?
Take toys out of cot and put away, repeating "we'll put your toys away, because it's not playtime, it's naptime, it's not playtime, it's naptime" etc etc (she has now added her own touch to this- waving bye bye to her toys, which is adorable).
Close curtains saying "we close the curtains, say bye bye daytime, it's naptime".
Put her in sleep sack- "we put you in your sleep sack, you're going to have such a nice nap, you'll feel so nice when you wake up, naptime darling" etc etc. Basically repeating the word "naptime" as many times as poss!
Put her in her cot ("we put you in your cot, give you your rabbit, night night for now, naptime darling", you get the picture).
Then leave the room saying night night for now, naptime etc as I go.
I sound absolutely insane don't I? But it does work, and this is the girl who used to only have a nap being rocked in her pram.
The first few days (she was about 5 months I think) it took a while to settle her, shush-patting etc. But she soon got the hang of it.
Her naps are woefully short, mind, but she goes to sleep like a dream!
ps It doesn't always work- hence the username- I came on here the other week when Madame decided that napping wasn't for her for a few days.