I used to work at a place that had a big long document on company-wide coding conventions. Some of the conventions were arbitrary and ugly, like prefixing all method parameters with a lower-case p (I came to realize that all of the variable prefixing made the code less readable, not more). We also had rules on where to write the curly braces, where to declare variables, how to name classes, etc.
Some of it was helpful, much of it was arguably unimportant, but all of it had to be followed because it was written up in a document and because "these are the conventions." I always thought programming was fun and following a rule book on conventions made it less so.
Instead of worrying about the rule book, I think it's important to focus on good style. Name stuff in a way that seems reasonable, be consistent with your syntax, etc. But focus more on making the code concise and simple. Don't clutter your code with lots of temporary variables, don't surround huge chunks of code in try-catches, break out pieces of functionality into functions. Writing code with good style is just fun, following conventions is not.
Also, keep in mind how the art of programming and technology itself changes, and, like a teenager, follow the trends. For example, the proliferation of multi-core systems has lead to a more functional style of doing things (immutable objects, etc). Keeping up with the latest is good for your code.
Finally, an excellent run-down of the latest in good Java style hit the internet today (and is my motivation for this post). I think it's right on the money: http://codemonkeyism.com/generation-java-programming-style/ Good coding doesn't mean following a static set of rules, but adapting new ideas for simple, elegant code that runs well.