Soft Proofing Isn't Hard
A friend once told me that one of the best things about digital photography is being able to make your own prints at home, and that one of the worst things about digital photography is trying to get those homemade prints to look the way they're supposed to. You print, you fiddle with the image, and you print again — over and over. There is a way out though, and it's called soft proofing.
The idea behind soft proofing is use your printer profile in a way to let you see on your monitor how an image will print, without actually printing it. If you haven't already figured it out, that means you need to have a printer profile specific to your printer model together with the type of paper you plan to print on. So long as you are printing on paper made by your printer manufacturer, the profile you need may well have come on the driver CD included with your printer or at least be available for download from their website. Epson has been providing ICC profiles for their photo printers for years and Canon and HP have since started doing likewise. If you don't have the needed profile, you'll need to get one from somewhere, either by making your own with a package such as X-Rite's Color Munki, or from third-party profile services such as Cathy's Profiles.
You'll also need a profile for your monitor. Unless you've profiled your monitor, there's no way you can tell if it's displaying your images accurately as determined by the RGB color numbers contained within the image. Those numbers mean something specific, and it is up to your monitor profile to make sure they get displayed correctly. Even if an image looks good on your un-profiled monitor, you can't really tell if that's how it really looks. All you can tell is that the colors in your image plus the adjustments on your monitor together look good. It's entirely possible to take an image with bad color and teak a monitor to improve how it looks, but the image itself won't have changed as a result. The monitor screen is essentially a filter that you view your images through and that filter can impart all sorts of color shifts without your being aware. So long as things look good on your screen, you can be fooled into believing your image is properly adjusted but such is not necessarily the case.
Soft proofing only works if you accept the necessity of color management. Otherwise, you can make an image look perfect on your monitor and still be disappointed when that image is rendered when it isn't affected by how your monitor is adjusted. You need your monitor to tell you the truth about what your images look like or none of this works. Your printer profile will not only be used to correct colors when it comes time to actually print, soft proofing uses it together with your monitor profile to show you on screen how those colors will print even before you turn that printer on. If you're a regular reader here you already know I'm a big believer in color management, and soft proofing is part of the reason why.
Before you soft proof, make whatever optimizations you need to so that your image looks the way you want it to, whether that is simply how you remember it when you shot it or some stylized version you augmented in your mind's eye. When you have the image looking great, save it so you have a master file you can come back to in the future. To actually make use of soft proofing, it depends on what software package you use to print with.
In Photoshop, go to View >> Proof Setup >> Custom. For "Device to Simulate" select the appropriate profile for your printer and paper. Rendering Intent should generally be Relative Colorimetric, but if you are printing on printer that supports only a limited gamut you may want to try Perceptual instead. Once you learn which intent works best for your printer, stick with it. The "Black Point Compensation" checkbox makes sure the darkest color in the color profile of your image gets mapped to the darkest color in the color space of your printer. Keeping this option checked will minimize the chance of color shifts during printing. "Simulate Paper Color" works better with some profiles than with others. When you actually print, the color of your paper is the whitest white possible and if your profile accurately captures what color that is, soft proofing can restrict your onscreen white point to match. A good printer profile will include this information but if you find you get a closer match without checking this option, leave it unchecked. And then start thinking about how you can get a more complete printer profile for next time if this is a paper you print on often. Never, ever check the "Preserve Numbers" checkbox. Doing so would completely defeat the idea of soft proofing since and is the equivalent of assigning your printer profile rather than converting color data using this profile. If you have proofing settings you use often, Photoshop also lets you easily save and load those choices under whatever name you choose.
Other programs have other ways of soft proofing since their menu structure will obviously differ although the labeling of each option is becoming more consistent than it once was. In Nikon Capture NX, there's a none-too-obvious dropdown box on the bottom border of each displayed image. Initially, it should say "Soft Proof Off." If you click on the small triangle next to it you'll get a dialog box where you can make your choices. Apple's Aperture implements soft proofing via the View >> Proofing Profile menu option. Oddly, Adobe Lightroom doesn't yet support soft proofing. If you use a something else entirely, you'll need to check the manual or help documentation to see what is available. Suffice it to say, Photoshop has the most complete feature set for soft proofing as it does for many things.
So long as you print using the same settings you chose during soft proofing, your final print should come out as a close match to the onscreen display. Given the inherent differences in how the two devices render color, it can never be a perfect match, but a profiled monitor and a good printer profile should get you darned close. Once you understand the basics, soft proofing isn't hard. And if you've been frustrated by trying to print your images at home and have them look like they do on your screen, it can be a godsend. Give it a try. You'll be glad you did.