with the afternoon nap i would go in just before or as she stirred, this meant standing at the door, and shh pat until she went back to sleep,
if it seemed like she was asleep i just raised my arm stood very still and waited 5 or so minutes, if she stirred again as i was walking out we would start again,
do you have quiet time before naps? i found this very important, we would go into dd room, clean it up, only have one toy which i would let her play with for 5 or so minutes, then i would hold her for 5 or so minutes until i could feel her calming down (as she got older this caused problems and only stirred her up, she want to calm down on her own), i would then put her in the cot and walk out,
if she cried not called out i would go in and assist to sleep, this was everytime at the beginning, once she had mastered going to sleep on her own i found it was then that things slowly improved with her sleeping longer, i did however have to assist her back to sleep for a time,
this is what i did, i only have one child and i have no other experience, one of the other things i did for a very long time was keep a diary of everything, from how long i shh patted, to how many time i had to reenter the room, how long she slept, everything, soon i saw a pattern, i used this pattern every day