Help with color picking

[SlimEddie]

Hey guys, so I was learning some pixel art stuff by basically looking at some one elses grass and using it as an inspiration.. I chose my own colors and that is where I got stuck.
Here is a grass with my colors:

And here is a grass colored using colors from the art I was looking at


Here is the link of art I was trying to mimic:
https://www.google.lt/imgres?imgurl=http%3A%2F%2Fi843.photobucket.com%2Falbums%2Fzz358%2Fmadmenyo%2F3D%2520and%25202D%2FGrass_double.jpg&imgrefurl=http%3A%2F%2Fpixeljoint.com%2Fforum%2Fforum_posts.asp%3FTID%3D11921&docid=bGXb_YSHmPWq6M&tbnid=YzZFMtABJ8bQwM%3A&w=256&h=256&bih=635&biw=1280&ved=0ahUKEwjvwOXEv_rOAhXMXCwKHTIrDaEQMwgoKA4wDg&iact=mrc&uact=8


The question is rather simple, how should I improve my color chosing skill?
how should I chose shades of color ( what should I alter ) when I have the base color or smth..?
What values should I alter when choosing shades (relates to upper question )...
Thanks in advance