napping in crib

So my son used to nap perfectly when he was using a bassinet but around 5 months he outgrew it. now he's finally gotten down sleeping in the crib at night but not naps. the past two months have been very hectic and we've either been out of town or had someone staying with us every other week it seems like, so I didn't really stick to it and have been giving in and letting him sleep in my arms, on the bed, in his car seat while we are out and about. now that i've been trying to get him to nap in his crib i can't figure out how to go about it. when i put him in drowsy but not asleep, he just wakes right up as soon as i set him down. so i leave him to see if he will fall asleep but he just plays or cries. and i keep trying to just calm him and put him back but he never ends up falling asleep and with naps i don't know how long i should try and stick to this. i mean, bottom line he still needs to nap right? so how long am i supposed to keep going with calming and setting him back down before he just becomes overtired and ends up missing his nap all together? i've also tried just letting him fall asleep before moving him because that's how we started out with bed times but he never seems to fall as deep asleep and will wake up when i set him down. what should i do? how do i go about getting him to nap in his crib? and how long am i supposed to keep trying each time before just letting him nap how he wants to so he can still get some sleep?