I think you're on the right path, jump into passes as soon as possible. I'd say you have the basics in maya to the point where you really need to start to look at the compositing process. Lots of people want the image perfect out of Maya before they start thinking about the next step. DON't do this! Take the image to post ASAP this will give you an idea of what needs fixing in maya and what you can get away with in post.

It will save you a ton of time and until you've seen for yourself what's possible in post you just end up wasting time rendering in maya. A lot of people get stuck where you are now because they don't get the fact that 50% of the image is done in Maya and 50% done in post, that ratio may vary of course but the sooner you start getting raw render information out of maya and into something like Nuke the better of you will be.

Hope that helps a bit
David