I want you to know how impressed I was when I looked at the line art first. Excellent inking! Especially when I read that you don't ink often. Do it more, you do it very well.
I adore an excellent inking job.
Now, your colour version...
There is one major trick in Photoshop that I am not sure if you are utilizing. Layers! Layers are totally your friend and you can use them do do anything! Try putting your lineart on the bottom layer and your color on the layer above it. Then set the color layer to "multiply" Multiply makes whatever is darker underneath the multiply layer show through. like this:
(Top Layer with NO Multiply)
(Top Layer with multiply switched on)
I usually like to block in my main colours first like above. Then, you can go on to the shading...
(Some shading added)
A quick little trick that I think is great for beginners is putting a third layer above everything with a colour. In this case, I chose a purple that I found in your original, and lightened it up a bit. I placed that on the top layer, set the layer on multiply, and changed the opacity to 50%.
(Top third layer is purple, multiply, opacity at 50%)
Then the trick is to use the eraser tool on the top layer and erase where you feel the highlights should be.
(Erase the third layer where highlights should be)
Important: Always color at a high resolution (200 and up). Why?
1)you may want to print it out and 300 dpi is standard for printing
2)You get sharper edges when colouring.
Remember:
Upload a pic to the internet at 72 dpi (That is internet resolution). You can knock your 300 dpi original down, and save another copy to upload.
ALWAYS SAVE A SEPERATE FILE WITH YOUR LAYERS!
you may want to go back and change it!
I hope that this gives you some ideas at the very least. I know it might not be your style of colouring, but totally experiment with layers. I hope you don't mind me using a section of your drawing for a demo. Say the word, and I will take it down. I just thought your original inks were so cool, I wanted to help.