Agree with willyoudothedamnedfanjo, timing is really important. If I miss sleepy signs then that can ruin things for the rest of the day. My DD needs to nap between 1.5- hours after wakening. Here is our routine to give you an idea...actual times dont seem to matter...
6.30am - breastfeed, nappy change, porridge, playtime
8/8.30am - breastfeed, nap
9.30/10.30am - nappy change, get dressed, breastfeed, playtime
12/1pm - nappy change, lunch, breastfeed, nap
The actual times vary most days - eg. yesterday my DD slept till 8am, but today she was up at 6am. BUT...I always offer her a breastfeed roughly an hour and half after her wakening as this seems to be when she is getting sleepy. I used to miss this and this resulted in NO naps at all and a very cranky baby 
If my DD is rubbing her eyes, yawning etc but will not feed, I still put her in her cot...somtimes this works, sometimes she screams, but the more I do it the more it works so I would persevere.
To put your mind at ease a little, my DD has not always napped. When she was younger she would sometimes not nap at all throughout the day.
I have ALWAYS tried to put my DD down in her cot for a nap (or moses basket when she was younger It is best to do it when they are slightly awake so that they learn to self settle but TBH most of the time my DD falls asleep while feeding and I am happy with this for now (she is 7 months)