I'm giving you my standard advice. Our doctor recommended it for us when my son was 9 months old and not sleeping at all! It saved our lives. Take whatever t-shirt you've worn that day and give it to your son 15 min. before bedtime. It should smell like you. Put him in his crib with some favorite toys, your shirt, a bottle of water and a binkie (if you use them). Stay by the crib as he tries to settle himself. I also have a fisher price aquarium that my son loves. He was able to turn it on and off at 8 months. He loves the lights and the music. Now, at 14 months, he can change the music! The first time I tried this, he clutched the t-shirt and breathed in deeply. He then put his head down on the shirt. Popped back up to look at me, head back down. Hand reached through the crib to touch me, smiled, and fell asleep.
That night, in the middle of the night, I heard him stirring. He got the bottle, took a drink, put the binkie back in his mouth, curled up on the shirt and went back to sleep. I hope this helps.
I also never cared too much where he napped. He often napped in his stoller, the carseat or even on me. Once we tried the t-shirt trick, it was easier to get him to nap in the crib. I save the shirt for naps and bedtime so he associates it with comfort and sleep. The other thing that helped me was the book, Good Night, Sleep Tight as I wasn't going to let him scream.
I hope all this helps. Sleeping and napping can be so stressful! I also try and put him in his crib when I'm folding his clothes and doing things in his room. I want him to see his crib as a fun place to be, with cool toys attached to the side. That way he doesn't see it as a lonely cage when you put him down and walk away. If he knows how to play in there, maybe he'll play a bit and then fall asleep without crying. My son does. What a magical day that was! Good luck!