Here's the finished picture of the rusted wrinkly tin.
I used the pigments to add some texture to the rusted areas,
I used Mig Productions Rust & added beach sand to lighten it for highlights,
these were mixed with car screen wash & dabbed on as appropriate
the when dry I rubbed of the pigment with an old brush if there was too much on.
I used mig pigment fixer was than used (surprisingly) to fix the pigment in place!
This is basically how I do rust,
whether its the same way as others do it I don't know.
It's the best way that I've found up to press, but things might change.