If you’re getting started with RCP, here are some resources that can help. I’ll try to keep this list current.
Eclipse Rich Client Platform 2nd Edition by Jeff McAffer, Jean-Michel Lemieux and Chris Aniszczyk is a good place to start.
I’d also recommend Eclipse Plug-ins 3rd Edition by Eric Clayberg and Dan Rubel. It’s not about RCP development specifically, but covers many of the APIs we commonly use.
The best book on SWT is SWT: The Standard Widget Toolkit by Steve Northover and Mike Wilson. Unfortunately it’s out of print but you can get it used and it’s also available on Safari (as are the other books I mentioned).
I’d also suggest getting familiar with OSGi, as this is really at the core of what RCP is all about. Neil Bartlett has a free online book called OSGi in Practice that I’d highly recommend.
On the web
As for tips and tutorials, there are a few sites with good information such as http://www.vogella.de and of course my own site. If you use RSS, I would highly recommend subscribing to the Planet Eclipse feed.
Finally, you may want to consider getting formal training as it can really shorten the learning curve!
In any case, best of luck with your RCP development. It can be challenging but it’s worth it!