Okay! I made a tutorial! It's friggin huge (and text-heavy), but I hope it's detailed enough that even people who haven't used Photoshop before can learn from it! I explain every step of the process as though you hadn't used Photoshop before so this might be a little tedious to people that know it well but...yeah. I won't explain how to get Photoshop, if you don't have it already, google it, it's incredible easy (not that I support that kind of thing...
cough)
Click for the tutorial! DO IT DO IT DO IT
And it works for all drawings, not just manga! As long as it's something black and white that you wanna colour. I've even coloured old photographs using the same method. If you make something with it (which I hope
somebody does), post it here! Or show it to your friends if you think they could use it, it's all good.
Also if anybody needs it in a bigger size, I have one 50% bigger...I just didn't wanna destroy people's browsers.