Proper use of the The channel mixer tool allows you to control how much each of the three color channels (red, green and blue) contribute to the final grayscale brightness. I find this to be the best black and white conversion methods, be rest assured however, it takes time to master.
In Photoshop open your color image and then click on Image > Adjustments > Channel Mixer
First click on the lower left tick box entitled "Monochrome" for black and white conversion.
Now get a feel for you image’s color channel distribution by sliding each of the color channels to 100% individually.
NOW Adjust each of the red, green and blue sliders to produce an image that you like. For more impact do not hesitate to try negative slider percentages.
In most cases the total of all the channel values should be close o 100% so as to maintain contrast brightness. You can however, adjust overall brightness by using the "Constant" slider at the bottom.
Note that the luminosity perceived by the human eye would have your settings at: red=30% green=59% blue=11%
Now click on "save as" and save this image.