The free tutorials on this site are a good place to start if you have not. Also the vip tutorials here are great learning tools as well, both for Organic modeling techniques and hard surface objects.
You can also search for tutorials on Google, there are numerous well thought out and put together tutorials that have been wrote up on peoples web pages.
another good way to learn things is to see if you can think of something you'd like to do, then try to find it in Maya's help docs... you might not find what you initially started looking for, but i guarantee you you'll learn something new nearly every time you delve into them, at least for a while anyway.
hope this helps
G-man