What criteria is used for determining gendered nouns?

When is it correct to add -ess to a noun to indicate the noun references the female gender? I have a good idea (or at least I thought I did) of which nouns change form based on gender, but what determines whether or not you can change the noun based on gender. I am fully aware that non-living and inanimate nouns are not candidates for the -ess suffix, but surely you would not say teacheress or assistantess or would/could you?
 
Back
Top