There are many ways how to convert color photo to monochrome, some work better than the others, the final look is a bit different depending how you choose to convert it. I used to do it with the black and white adjustment layer directly in PS before, but recently i found that i love doing it more in Camera Raw. Maybe color algorithms are a bit different there than in PS but it certainly gives a different look.
I can do workflow video with the Black and White layer in PS too if you are interested, so just let me know in the comments below.
Please keep in mind that this is my first tutorial ever, so the presentation might not be as polished as you expect it but i hope that you at least will find it useful and apply the knowledge in your workflow if needed.. I promise i will try to improve my presentation skills :)