looking for tips on colouring.

I was wondering if you would give me a few tips.
Mainly on how to make graduated colouring. My icons are always kind of blocky in colour, and slightly vulgar because they're too bold and there's no real 'pop' to them.
eg.

Whereas, I would like to have a sort of subtle graduated colour- that has life to it eg.

codestothestars@squaresided \ chouchoune@2cheatedhearts


chouchoune@2cheatedhearts

Mainly, my problem is that I don't know how to use gradients properly. And I have played around, but I can never get such subtle changes- I can't get good colour. I mostly use selective colouring and curves, yet it's always blocky for me.
Please help.

I use PS CS2.

Thank you.