Centauri's "The Definitive Guide to the Weapon Finish"
Recommended by Valve themselves during their "Dreams & Nightmares" skin contest, The Definitive Guide features 140+ pages of information about the skin making process. Great for both those just starting out, and well-seasoned designers.
The Definitive Guide to the Weapon Finish http://The Definitive Guide to the Weapon Finish



Hollandje's "How to make your own skins for Counter Strike Global-Offensive"
Paired best with The Definitive Guide, Hollandje's eight part YouTube series covers the ins and outs of skin making, from downloading the programs to uploading your design to the Steam workshop.
Hollandje's Skin Making
http://Hollandje's Skin Making


r/csworkshop Subreddit
Super useful community modded by workshop artists Quzga, Ezikyl_, and Hollandje. Definitely worth looking into if you use Reddit, it's a fantastic place to get your skin making questions answered!
http://r/csworkshop




CSGO Workshop Discussions Page
http://CSGO Workshop Discussions

Valve's "Workshop Style Guide"
"Valve's Workshop Style Guide" http://Valve's Workshop Style Guide

Valve's "Weapon Finishes Guide"
"Valve's Weapon Finishes Guide" http://Valve's Weapon Finishes Guide

I was five and she was six
We rode on horses made of sticks
She wore black and I wore white
She would always win the fight

Bang bang!
She shot me down
Bang bang!
I hit the ground
Bang bang!
That awful sound
Bang bang!
My baby shot me down

Seasons came and changed the time
When I grew up, I called her mine
She would always laugh and say
Remember when we used to play?

Bang bang!
I shot you down
Bang bang!
You hit the ground
Bang bang!
That awful sound
Bang bang!
I used to shoot you down

Music played and people sang
Just for me the church bells rang