Far better to start

Hi guys,

I came across this sentence from an article on coffee history:

"Who would buy such a product (=coffee) whose properties, uses, and preparation were a complete mystery to him? Far better to start by selling the already brewed beverage from little stands or shops, in order to build up a demand."

I know before "Far better" , "it is" is deleted. --> It is far better to start

my question is, when (in what situation) can "it is "be deleted?

Thank you for your help in advance.