Since I went to school for marketing and PR fell in my lap at my current job, I have been learning PR as I go. I rely on many of the industry experts and try to read as much as I can about all things PR. Here are some of my favorite sources for great information.
As for tips for contacting journalists, use common sense. Don't send attachments, keep a pitch short and sweet, don't call unless asked to and be sure that you know what beat the journalist covers!
Here's a funny and helpful article regarding contacting journalists:
Don't be a flack: Tips for PR workers from the journalists who hate them
http://valleywag.com/tech/flacks/dont-be-a-flack-tips-for-pr-workers-from-the-journalists-who-hate-them-200494.php
PR News & Resources
Bill Stoller's PublicityInsider.com
Holmes Report
O'Dwyer's Public Relations Daily
Online Public Relations
PRWeek
The Publicity Hound
And the best new resource for journalist queries:
Help a Reporter
http://www.helpareporter.com/