Vuescan
I honestly do not recall the source of this information, would not be surprised if it is from a fellow RFF member; I apologize for not being able to give credit to the author
Here goes:
First off, it is better to scan your black and white, or color negs, as slides. The scanner and Vuescan will utilize every ounce of their potential when in this mode. It makes a difference! Set to "slide film" as apposed to "image".
Set the optical resolution/pixels to the highest the scanner is rated for optically, as apposed to having it interpolate the data. Set it for the highest bit depth available, but you will not benefit from the RGBI setting (though I don't think the Dimage has an infrared channel, so that option wouldn't likely appear). You can leave the preview res on auto. I'd leave the number of passes at one, and not use the long pass option. You may benefit slightly from them on a poor (very poor) exposure, but they are generally not needed, and can cause softening of the image.
This is where it gets important! Go down and set the "Lock Exposure" option. After doing so, the box below "RGB exposure" will have a value in it. If it isn't "1", you'll need to set it to that value. This will give you more options and control. "Exposure clipping" I always keep at zero, which is probably best. Down below that, you'll want to check "Lock film base color", and "Lock image color", so you'll have more control over the histogram and within the color options tab.
After setting these options, you should be fine to do the preview scan. Once complete, go to the "Preview Hist." view, and the color tab. From there, set the film base color for all three, red, green, and blue, to zero. From there you can use your mouse to move the three colored triangles for both the white and dark points. I never bother to use this for the actual white and black point, but rather to get the scan as nuetral as possible. You can do this by aligning all three channels to meet directly where they touch the bottom of the scale. Do this for both the right and left sides of the histogram, and the image will scan almost perfectly grayscale.
This method is the best for insuring you get the most possible information from the neg and into the computer, where I assume you'll be further editing it. I always hit channel mixer in PS and check the monochrome box and hit okay. That removes the slight color casts that you will always have. Next, I use curves to flop the image into a positive; just pull the top right corner down to the bottom, and the bottom left up to the top, and you're in business. You can complete other edits as you normally would.
