(Oliver from Silktide here, I wrote that article).

Might be useful to see our own Terms, they're still online here:

www.silktidestudios.com/tandc

We always charged 50% upfront for anything over £1,000 (about $1,600). Projects over around £20,000 usually had three way splits.

Of course some bigger contracts (esp. government) insist on their own onerous terms but usually they're decent payers.

Hmm. Perhaps I should write an article on getting this too...