I have a big, big one down the middle, honestly one of the biggest and bluest I've ever seen, I'm getting veiny and like it. I have noticed a newer one currently growing, its about 2/3 of the way up the shaft on the right hand side, its medium sized and forks off into two.
Jelqing is the thing for veins in my opinion, try clamping at the bottom, then raising that hand about half-way up your shaft with pressure still applyed, then kegel, watch the veins bulge...