Nice job. I'm a rookie here too, so welcome to the boards!
The green lines are nice and straight. What kind of paint and/or sealant did you use? I only ask because he looks a tad too glossy, but that could be due to camera flash, or the fact that it's got shiny clear plastic all around it.
As for the black lines, I assume they're battle damage, or just wear and tear. For blaster marks, I put a bit of black ink on my finger or a qtip, then just "punch" a spot on the figure. I'd suggest you blur those lines a tad to make it look more authentic.
All in all a great start to customizing.