The absolute best site I've discovered provides a wonderful succinct explanation of LR functions, menus and settings:
Learn Lightroom in a week detailed ilustrated tutorials
I discovered that it is vital to understand the "catalogue" function of this software if any semblance of control is to be maintained over images. Digital Photography School provides some great hints commencing with a comparison between 'destructive' and 'non destructive' editing which was eminently helpful. To paraphrase and summarise :
1. Non destructive editing - means any modifications made to an image are not changing the original image. Photoshop by comparison is an example of a destructive editor as changes made to an image are saved directly over the original image, thus destructively editing the original file.
2. Lightroom Previews - When you see changes being made inside of Lightroom as you adjust "Develop: settings, what you are seeing is actually just a “preview” which won’t actually be applied to the image until you “Export” the image from Lightroom. To save time, it is recommended that prior to developing you “Render 1:1 Previews” for all of your images by going into the Library Module, turning off all filters so all images are visible, then selecting the following from the menu "This saves time during developing since Lightroom will no longer have to pause to render a preview or zoom into an image.he .lrcat file" only contains information like a giant database. The actual images ARE NOT being stored in the Lightroom Catalog. Lightroom is simply referencing those images at a particular location on your hard drive. Knowing this is important because when Lightroom asks you if you want to “backup your Lightroom Catalog” you know then that you are only backing up the information and not the actual images themselves.
5. One Catalog or More? - We often are asked whether photographers should have only one Lightroom Catalog for all of their images, or have multiple Lightroom Catalogs for every single shoot. There are most certainly benefits to each. Since Lightroom catalogs are independent of each other, images within other catalogs cannot be searched and found from Lightroom, unless that specific catalog is open.
6. Recommended Best Practices - for the event shooter who frequently captures around 1000+ images per event/shoot, create a Lightroom catalog for each event as efficiency is the primary priority since you need to be able to move through catalogs, edit, transfer and archive at a good speed.
I love the clear method worm3245 has of explaining. I found his videos amongst the best for shedding light on the basics.
Lightroom 3: Set-up and Importing - Part 1
Lightroom 3: Set-up and Importing - Part 2
Lightroom 3: Set-up and Importing - Part 3
Lightroom 3: Enhancing Raw files
Lightroom 3: Which file format is better? PSD vs Tiff??
Lightroom 3: Developing Images
Developing Images #2
Lightroom 3: Collections Explained
Lightroom 3: Filters Panel Explained
10 Quick and easy Lightroom Tips
Good Summary for default preferences
Flickr's Preset links
Lightroom Shortcut Keys ( hot keys)
Post Processing Tony Northup style