Are you self taught? Could you possibly recommend be a guide?
well. you should really check some photoshop tutorials...just to improve your skills with some tools.
for example this one was one of my first sigs. just to check what i can do with brushes, filters and other stuff:
and one of my last sigs you can see below. its just practice
Looks good man. Rumors there are a ton of tutorials out there if you look online especially on youtube.
If you can pick up on photoshop that would be best or even just paint on pc. You can do a ton of stuff with just brushes, overlays, values, and filters like razer said, but you get a lot better with time. Its all just trial and error to see what works / looks good.
I self tought myself in photoshop which lead me to become a graphic designer. But mainly use indesign and illustrator for my design work.