Before any tutorials or suggestions to folks that they start messing with system settings-like monitor color temperature and profiles, we better be on the right page of the manual.
In practice
and the absence of a specific calibration package like those from Pantone/Huey/Gretag-Macbeth/Monaco/or SpyderVision the notion of resetting the monitor color temp to a lower color temp is good advice. This has little to do with the monitor and more to do with the fact that we use mostly tungston lighting in our homes. It's C-temp is about 3500K.
With any of the above packages, a step to reset the monitor color temp is included in the process and the specific directions call for setting the temp of the monitor to
match the temp of the light surrounding the monitor. Matching in this fashion is the greatest possible relief for eye strain. It is synonymous to the WBing done in camera!
Precise matching would require a Light Color Temperature Meter, an expensive luxury. The simplest solution is to use your camera custom WB feature and a white card in the 'surrounding light'; match the WB temp in the EXIF of a sample image of the working environment around the monitor to enter the appropriate value into the calibration software editbox.
Third party profiles are provided for Soft Proofing; "what
might the print look like if sent to xyz printer
is shown on the users monitor---it's a best guess assuming good monitor calibration and profiling and very useful for certain green-yellow and red-orange problems.
Costco and the source of their profiles:
"http://www.drycreekphoto.com/Learn/profiles.htm"] (and most other color space aware printing organizations) state(s)
quite clearly that they EXPECT an sRGB color space tag on a file sized to 300 ppi for the desire output, i.e 1200 by 1800 pixels for a 4 by 6 inch print.
To use the Costco profile as the tag might cause double application of the same profile. This will generally not occur if the file header and the EXIF are included with the submission--software is supposed to recognize the input colorspace tag.
This is usually why folks get away with improper tagging. If for some reason the header and the EXIF tag are deleted or damaged and the print software is asked to assume a profile, it will assume sRGB and the print will be wrong. Many low priced/third tier (P&S) cameras and similar (proprietary) editing packages produce a protocol correct, basic JPEG (one without a colorspace tag). Assigning other than sRGB will be a disaster.