I started noodling with Final Cut Pro soon after it came out (ten years ago!) and taught myself how to use it. By taught, I mean that I learned to hack my way around and accomplish what I needed. But it wasn't pretty or fast. After a few years, I really started feeling the limitations of my abilities, so I decided to dig into some tutorials. For whatever reason -- probably because I'd seen a few for free online -- I chose Larry Jordan's Lynda.com video tutorials. These helped me immensely with everything from media management tips to techniques that greatly reduced the time I'd spend fumbling through FCP's interface.
Even if you don't need to teach (or re-teach) yourself Final Cut Studio, I highly recommend that you check out Larry's free Monthly Newsletter. Among the tips this month:
Startup Mode Selector, a free application that helps Snow Leopard users learn more about, and harness, 64-bit technology without use of the terminal...
Ken Stone's excellent iChat Theatre tutorial...
and Apple's substantial (40pages) white paper on Customizing Final Cut Studio Blu-Ray Disc Templates.
Enjoy.