I just figured out the key to getting my little guy to take great naps and figured I would save some of you a headache if possible. Make him sleep more! I had always heard/read that if a baby gets overtired, it's harder for them to fall asleep, but had no idea just how true it is.
My 2 1/2 month old son has been fighting naps, waking up 30 minutes into them, cat napping all day, etc. I am a big time planner/scheduler and apparently needed "guidelines" to help me. I read not to let your baby go more than 2 hours awake and dont' accept any naps less than 1 1/2 hours (ie: if they wake up before that, let them cry/fuss back to sleep until it's been 1 1/2 hours...). This may not jive with all of your parenting styles but this takes the stance of the parent dictates the schedule, not the baby, but turns out I know what my baby needs more than he does at this point, haha! Oh my gosh - immediately my baby started sleeping during the day (night was never a problem) perfectly! Here I was keeping him up because he seemed happy and content playing, but after 2 1/2 - 3 hours, he would become so tired so quick, that he wasn't able to fall asleep on his own and couldn't transition from the first stage of sleep to REM sleep which usually occurs between 30-45 minutes which is why he can't waking up and taking such short naps. I'll admit, this does get tricky to figure out a schedule if he's eating every 3 hours and napping every 2, but I figured it out and he is SO much happier, I am getting so much more done around the house and my arms are thanking me for not having to jiggle him back to sleep for an hour each day!
So, moral of the story is DON'T LET YOUR BABY BE AWAKE FOR MORE THAN 2 HOURS AND DON'T ACCEPT A NAP LESS THAN 1 1/2 HOURS. I hope this helps someone as much as it did me!!