If your gradient map looks like it hasn't done it right try desaturating (Ctrl+shift+U or using the the HUE colour slider mask) and it might make a big difference. Also once finished try playing around with levels or curves to get a nicer and more contrasty result!
............................................................................................
Nothing really else to say here, it's all up there ^^ Apart from if you get stuck comment me below,

, enjoy!
Try to comment or

if you learned something.
James-Dolan
Thanks