This is an edited copy of something I wrote to a friend who is a part-time photographer incidental to her main activities when she was starting out with Lightroom, so apologies if it talks about some things which are below the necessary expertise threshold for some people. I thought it might be useful for people starting out with the transition to Lightroom:
Lightroom is the way to go, but it won't be completely painless; but it WILL be worth the pain.
Lightroom is both Mac and PC, and you can install a copy on each from the same purchase - you don't have to buy a PC version separate. Unlike Aperture.
How can I give you some useful guidance? I think by getting to basics.
In LR, your images are kept separate from the metadata information about them, which is kept in a database. But unlike iPhoto, you always know exactly where your image files are in the file system. The filing system shown in the LR desktop is the same as on your hard disk. And writing the information actually to the file when you need to is easy.
The metadata stored in LR breaks down into three parts; the exif data which your camera writes into the file, the IPTC/XMP data you create - caption, keywords, contact and copyright information - and the image processing data. You won't normally need to change the exif data (stuff like shutter speed, aperture, lens info, flash on/off, camera identification, date shot). You will want to add IPTC/XMP info to any files you send, and captions and keywords make finding images easy.
Now for the image processing. An image is essentially a collection of pixels, each of which has colour and brightness. When you shoot, information is collected for each pixel and stored digitally. If you shoot raw files (nef files for Nikon), then the information for each pixel is stored. If you shoot jpeg, then some of this information is lost, because similar adjacent pixels are added together - sort of 'pixels 1 to 1234 are all close to these values, so I'll store 1:1234=colour a, brightness b'. This is how jpeg images can be much smaller than nefs. High quality jpegs (larger images) look for pixels that are closer in colour/brightness to each other than low quality jpegs (smaller images).
When you adjust an image in Photoshop, you change the values of the colour/brightness of the pixels, destroying some of the original data, so it's called destructive editing. When you adjust an image in LR, all you do is create a file with information about how those original pixels should be viewed - a kind of digital filter that goes on top of the original pixels - so LR uses non-destructive editing, which means you can always go back to the original information if you want to.
When you need to send a picture to someone, LR outputs it, with your adjustments and your captions etc, to a jpeg.
When you install Lightroom, you have several modules: Library, Develop, Slideshow, Print, Web. In Library you can do very basic colour, tone, white balance, etc. adjustments in 'Quick Develop', and you can do captioning and keywording. In Develop, you do more detailed image adjustments. The others do what they say!
Once you find your way around it becomes very easy to do all of the things you used to do in several other programmes - you can even upload picture galleries direct to your website (as on the IPCST site) from within Lightroom. (For forum readers: IPCST is the charity we run: www.ipcst.org)
There's lots more you can do, but that'll do for now; except to say that you can add stuff like contact and copyright information as you download from your camera (or as you import the images from your hard drive).
A few words of advice:
1. Keep your file system simple. I use the file names allocated by the camera, which is set to give them sequential numbers from '''1 to 9999 with a ABC prefix. The default when you import is that LR stores them in date folders yyyy-mm-dd in a year folder yyyy, and that is the system I use. With the power of Lightroom you can always find the picture you want (as long as you do the captions) so you don't need a complicated filing system.
Ok so here I need to mention one more feature of LR. In the Library module, below the 'Folders' pane is a 'Collections' pane. You can set up as many 'virtual folders' here in which you can group your images in as many ways as you like. A single image, with only one actual file, can be in as many 'collections' as you like. So you can create a 'virtual file system' just as you would if you normally store your images in a series of folders for different purposes, or for different types of images. But the image files themselves will stay in your date organised folder system. You can always find out where the actual file is; right click (option-click on a Mac without two buttons!) and choose 'show in Finder/Explorer' or 'Show in Folder in Library'.
If you already have your files in a complex system, you can keep it, or you can choose 'Copy photos to a new location and import' in the dialogue which opens when you choose File>Import Photos from Disk, to create a new copy of your photos in the date filing system (later, when you are happy with LR, you'll be able to delete the originals!). LR will automatically read the original shoot date from each file and set up the filing system accordingly, assuming that these are digitally-originated images rather than scans.
2. If you have lots of files with the same file names, you can use the powerful LR file renaming system to create a new file naming system (I don't rename my files).
3. Set up a Metadata preset in the 'Information to Apply' section of the Import Photos dialogue, with your name, contact details and copyright info, and apply it to your photos as you import. You can set up lots of these, or update it to include some basic captions and keywords applicable to all the photos in a specific import.
4. When you import photos from your camera, you can immediately make a backup copy to an external hard drive by ticking the 'Backup to' box.
5. Early on, if you are going to use keywords extensively, you need to think out how you are going to set up your 'Keyword Tags' hierarchical keywording system. This is quite complex, and you will need to do some research on the Internet.
That's the end of Lightroom correspondence course lesson 1.