A sock mockup is not a luxury. It is a necessity. If you are ordering custom socks, you should never guess what the final product will look like.
A good sock mockup design guide starts with the sock style. Are you making custom crew socks, ankle socks, or custom dress socks? Each shape changes how the artwork sits. A logo that looks great on a crew sock may look cramped on an ankle sock.
Next, think about placement. Custom logo socks usually put the logo on the cuff or the leg. Full patterns can wrap around the whole sock. For custom printed socks, the mockup should show how the design connects at the seams.
Then there is color. Screen colors and yarn colors are different. A mockup helps you catch problems before production. If you are working with a custom sock manufacturer, ask for a physical sample if the design is complex.
At SOXFUN, mockups are free and revisions are unlimited. We would rather spend a day on the mockup than have you receive 500 pairs you do not love. That is how custom socks should work.