Question

if you breed a serperior with a ditto, is there a way to have a bigger chance of getting a shiny snivy

Answer 1

The only way would be using the Masuda method, meaning the two pokemon you're breeding are from different Countries than each other.

This is the only effective way to increase your chance of getting shinies When Breeding.

So you could easily do.. ( Lets say you're American )

American Serperior + Japanese Ditto

And you would have a better chance of getting a shiny, although the chance is still 4/8192.