There are somewhere in the neighborhood of 8,000 ways to convert an image to black and white, but of course, not all methods are equally effective or offer the same level of control over the final product. This method takes a bit more time than most, but will give you the exact results you desire.
Coming to you from Unmesh Dinda of PiXimperfect, this helpful tutorial will show you a more advanced method for converting images to black and white. The basic problem of the procedure is deciding how exactly to map different colors to grayscale values. The most basic way to do it is to simply drop the color information and retain only luminance values, but it's rare that this creates the most desirable conversion, which is why Photoshop offers the color sliders in the black and white adjustment layer dialog, as most photographers prefer some level of control over the mapping. The beauty of this method is that it allows you the utmost control by honing in on the exact color range you'd like to work on and allowing you to use layer masks to control its application. It's definitely more time-consuming than most, but the results are worth it. Give it a try!