Are there any helpful/tips email newsletters one could subscribe to for Mac OS X?

Not that I know of'; however, I learned a great deal by just reading some of the discussions in these forums. So, if you're interested in a certain OS version, simply go through that, learn by checking where the reported problem is and try out suggestions offered.

You'll be amazed at the level of knowledge of the longtime participants here - I've learned a great deal from them (and continue to learn something new all the time).